diff --git a/Code Files/ContactList.txt b/Code Files/ContactList.txt
index b88b387..127332e 100644
--- a/Code Files/ContactList.txt	
+++ b/Code Files/ContactList.txt	
@@ -1,11 +1,11 @@
 suresh kumar m 8422882287 thane
 abrar shaikh m 8545525632 malegaon
+roshni verma f 8422882286 majiwade
 aditya tiwari m 7594854565 thane
 rajesh sharma m 8924073774 panvel
 ganesh mourya m 9137141840 thane
+karan kumar m 8422882284 thane
 gaurav manohar m 9021409095 kalyan
 mukesh patel m 8452458565 kurla
 asha vishwakarma f 7595455412 thane
-karan kumar m 8422882286 thane
-roshni verma f 8422882286 majiwade
 sahyog college m 8422882285 thane
diff --git a/Code Files/main.c b/Code Files/main.c
index 01ef4e8..4b14c03 100644
--- a/Code Files/main.c	
+++ b/Code Files/main.c	
@@ -1,13 +1,16 @@
 /*
     Project Title: Phonebook Management System 
     Language: C 
+    GitHub Repository: https://github.com/Alkaison/Phonebook-Management-System 
+    BSc IT Course => Project for Semester-1  
     Concepts: File Handling, Struct, Define, etc. 
 */
 #include<stdio.h>  // almost everything 
 #include<stdlib.h>  // system() 
 #include<string.h>  // strcmp(), strlen() 
 #include<conio.h>  // getch() 
-#include<windows.h>  // Sleep() 
+#include<windows.h>  // Sleep() => for windows OS 
+#include<unistd.h>  // for linux or Mac OS 
 #include<ctype.h>  // isdigit(), isaplha() 
 
 // define constants -> is used to define the constant or the micro substitution 
@@ -51,6 +54,7 @@ void adminPanel();
 int isValidGender(char *gender);  // checks for the gender input 
 int isValidNumeric(char num[]);  // checks for the phone number input 
 int isValidName(char *name);  // checks string for searchByCity & searchByName  
+int checkNumberExistence(char *num);  // checks for the input number if its exists in the database or not 
 char *removeSpaces(char *str);  // removes empty spaces from name inputs 
 void invalidInput(int);  // shows error on invalid inputs and returns them back to the panel 
 void clearBuffer();  // clears the output screen & input buffer 
@@ -135,7 +139,11 @@ void endScreen()
     printf("\n\t\t\t\t------------------------------------------ \n");
     printf("\t\t\t\t   >>> Phonebook Management System <<<     \n");
     printf("\t\t\t\t------------------------------------------ \n\n");
-    printf("\t\t\t\t\t\tThank You. \n\n");
+    printf("\t\t\t\tGitHub: https://github.com/Alkaison \n");
+    printf("\t\t\t\tTwitter: https://twitter.com/Alkaison \n");
+    printf("\t\t\t\tLinkedIn: https://linkedin.com/in/Alkaison \n\n");
+    printf("\t\t\t\t------------------------------------------ \n");
+    printf("\t\t\t\t\t\tThank You. \n");
     printf("\t\t\t\t------------------------------------------ \n\n");
     Sleep(1500);  // pause the screen for 3 seconds 
     exit(0);  // ends the program safely 
@@ -354,6 +362,22 @@ int isValidNumeric(char num[])
     return 0;
 }
 
+int checkNumberExistence(char *num)  // checks for the input number if its exists in the database or not 
+{
+    FILE *pT = fopen("ContactList.txt","r");
+
+    while(fscanf(pT, "%s %s %c %s %s\n",copy.firstName, copy.lastName, &copy.gender, copy.findNum, copy.cityName) != EOF)
+    {
+        if(strcmp(num, copy.findNum) == 0)
+        {
+            fclose(pT);
+            return 0;
+        }
+    }
+    fclose(pT);
+    return 1;
+}
+
 void invalidInput(int entryCode)
 {
     printf("--------------------------------------------- \n");
@@ -419,13 +443,22 @@ void addNewContact()
         {
             if(isValidNumeric(contact.findNum) == 1)
             {
-                removeSpaces(contact.firstName);
-                removeSpaces(contact.lastName);
-                removeSpaces(contact.cityName);
-                fprintf(pF, "%s %s %c %s %s\n", contact.firstName, contact.lastName, contact.gender, contact.findNum, contact.cityName);
-                printf("---------------------------------------------- \n");
-                printf("Success: Contact details added in the record.  \n");
-                printf("---------------------------------------------- \n");
+                if(checkNumberExistence(contact.findNum))
+                {
+                    removeSpaces(contact.firstName);
+                    removeSpaces(contact.lastName);
+                    removeSpaces(contact.cityName);
+                    fprintf(pF, "%s %s %c %s %s\n", contact.firstName, contact.lastName, contact.gender, contact.findNum, contact.cityName);
+                    printf("---------------------------------------------- \n");
+                    printf("Success: Contact details added in the record.  \n");
+                    printf("---------------------------------------------- \n");
+                }
+                else
+                {
+                    printf("---------------------------------------------------- \n");
+                    printf("ERROR: Phone number already exists in the database. \n");
+                    printf("---------------------------------------------------- \n");
+                }
             }
             else
                 flag = 1;
@@ -490,53 +523,25 @@ void updateContact()
             printf("Enter the city name: ");
             gets(copy.cityName);
 
-            printf("Enter the gender [M/F]: ");
-            scanf(" %c",&copy.gender);
-            fflush(stdin);
-            
-            printf("Enter the phone number [+91]: ");
-            gets(copy.findNum);
-
             fflush(stdin);
             printf("\n");
-            removeSpaces(copy.findNum);
-            if(isValidGender(&copy.gender))
+
+            printf("Type `CONFIRM` to update this details: ");
+            gets(confirmDelete);
+            if(strcmp(confirmDelete, "CONFIRM") == 0)
             {
-                if(isValidNumeric(copy.findNum) == 1)
-                {
-                    printf("Type `CONFIRM` to update this details: ");
-                    gets(confirmDelete);
-                    if(strcmp(confirmDelete, "CONFIRM") == 0)
-                    {
-                        // validates everything and fetchs into file 
-                        removeSpaces(copy.firstName);
-                        removeSpaces(copy.lastName);
-                        removeSpaces(copy.cityName);
-                        printf("\nProcessing . . . \n\n");
-                        fprintf(pT, "%s %s %c %s %s\n",copy.firstName, copy.lastName, copy.gender, copy.findNum, copy.cityName);
-                        flag = 2;
-                    }
-                    else
-                    {
-                        flag = 1;
-                        fprintf(pT, "%s %s %c %s %s\n", contact.firstName, contact.lastName, contact.gender, contact.findNum, contact.cityName);
-                    }
-                }
-                else
-                {
-                    fprintf(pT, "%s %s %c %s %s\n", contact.firstName, contact.lastName, contact.gender, contact.findNum, contact.cityName);
-                    if(len == 0)
-                    {
-                        printf("--------------------------------------------- \n");
-                        printf("ERROR: Invalid input please try again later.  \n");
-                        printf("--------------------------------------------- \n");
-                    }
-                }
+                // validates everything and fetchs into file 
+                removeSpaces(copy.firstName);
+                removeSpaces(copy.lastName);
+                removeSpaces(copy.cityName);
+                printf("\nProcessing . . . \n\n");
+                fprintf(pT, "%s %s %c %s %s\n",copy.firstName, copy.lastName, contact.gender, contact.findNum, copy.cityName);
+                flag = 2;
             }
             else
             {
+                flag = 1;
                 fprintf(pT, "%s %s %c %s %s\n", contact.firstName, contact.lastName, contact.gender, contact.findNum, contact.cityName);
-                flag = 3;
             }
         }
         else
@@ -721,14 +726,22 @@ void displayContact(int entryCode)
     printf("\t\t\t\t---------------------------- \n\n");
     pF = fopen("ContactList.txt", "r");
 
-    printf("\t\t|===============================================================| \n");
-    printf("\t\t|ID| \tName\t\t| Gender | Phone Number\t| City Name\t| \n");
-    printf("\t\t|===============================================================| \n");
+    if(fscanf(pF, "%s %s %c %s %s\n",contact.firstName, contact.lastName, &contact.gender, contact.findNum, contact.cityName) != EOF)
+    {
+        printf("\t\t|===============================================================| \n");
+        printf("\t\t|ID| \tName\t\t| Gender | Phone Number\t| City Name\t| \n");
+        printf("\t\t|===============================================================| \n");
 
-    while(fscanf(pF, "%s %s %c %s %s\n",contact.firstName, contact.lastName, &contact.gender, contact.findNum, contact.cityName) != EOF)
-        printf("\t\t| %d| %s %s \t| %c |\t %s \t| %s \t| \n", counter++, contact.firstName, contact.lastName, contact.gender, contact.findNum, contact.cityName);
+        do
+        {
+            printf("\t\t| %d| %s %s \t| %c |\t %s \t| %s \t| \n", counter++, contact.firstName, contact.lastName, contact.gender, contact.findNum, contact.cityName);
 
-    printf("\t\t|===============================================================| \n\n");
+        } while(fscanf(pF, "%s %s %c %s %s\n",contact.firstName, contact.lastName, &contact.gender, contact.findNum, contact.cityName) != EOF);
+
+        printf("\t\t|===============================================================| \n\n");
+    }
+    else
+        printf(" ERROR: Either we are unable to locate the ContactList.txt file or\n\t there are no contacts saved in the file. \n\n");
 
     fclose(pF);
     system("pause");
diff --git a/Images/UseCaseDiagram.png b/Images/PMS_00_UseCaseDiagram.png
similarity index 100%
rename from Images/UseCaseDiagram.png
rename to Images/PMS_00_UseCaseDiagram.png
diff --git a/Images/PMS_01_Information_Page.png b/Images/PMS_01_Information_Page.png
deleted file mode 100644
index ca1d01a..0000000
Binary files a/Images/PMS_01_Information_Page.png and /dev/null differ
diff --git a/Images/PMS_01_Introduction_Screen.png b/Images/PMS_01_Introduction_Screen.png
new file mode 100644
index 0000000..bf53823
Binary files /dev/null and b/Images/PMS_01_Introduction_Screen.png differ
diff --git a/Images/PMS_02_Login_Page.png b/Images/PMS_02_Login_Page.png
deleted file mode 100644
index 4ab6263..0000000
Binary files a/Images/PMS_02_Login_Page.png and /dev/null differ
diff --git a/Images/PMS_02_Login_Screen.png b/Images/PMS_02_Login_Screen.png
new file mode 100644
index 0000000..3cd52b5
Binary files /dev/null and b/Images/PMS_02_Login_Screen.png differ
diff --git a/Images/PMS_03_Admin_Login_Secure.png b/Images/PMS_03_Admin_Login_Secure.png
new file mode 100644
index 0000000..c400cca
Binary files /dev/null and b/Images/PMS_03_Admin_Login_Secure.png differ
diff --git a/Images/PMS_03_Secure_Password.png b/Images/PMS_03_Secure_Password.png
deleted file mode 100644
index f047b74..0000000
Binary files a/Images/PMS_03_Secure_Password.png and /dev/null differ
diff --git a/Images/PMS_04_Admin_Panel.png b/Images/PMS_04_Admin_Panel.png
index 0061d27..1f6d6f3 100644
Binary files a/Images/PMS_04_Admin_Panel.png and b/Images/PMS_04_Admin_Panel.png differ
diff --git a/Images/PMS_05_User_Panel.png b/Images/PMS_05_User_Panel.png
index 34165cd..5cc1b03 100644
Binary files a/Images/PMS_05_User_Panel.png and b/Images/PMS_05_User_Panel.png differ
diff --git a/Images/PMS_06_AddNewContact.png b/Images/PMS_06_AddNewContact.png
new file mode 100644
index 0000000..126f08e
Binary files /dev/null and b/Images/PMS_06_AddNewContact.png differ
diff --git a/Images/PMS_06_Add_New_Contact.png b/Images/PMS_06_Add_New_Contact.png
deleted file mode 100644
index 758c29a..0000000
Binary files a/Images/PMS_06_Add_New_Contact.png and /dev/null differ
diff --git a/Images/PMS_07_UpdateContact.png b/Images/PMS_07_UpdateContact.png
new file mode 100644
index 0000000..f6e1b10
Binary files /dev/null and b/Images/PMS_07_UpdateContact.png differ
diff --git a/Images/PMS_07_Update_Contact.png b/Images/PMS_07_Update_Contact.png
deleted file mode 100644
index 16d1e02..0000000
Binary files a/Images/PMS_07_Update_Contact.png and /dev/null differ
diff --git a/Images/PMS_08_DisplayAllContacts.png b/Images/PMS_08_DisplayAllContacts.png
new file mode 100644
index 0000000..0b306bc
Binary files /dev/null and b/Images/PMS_08_DisplayAllContacts.png differ
diff --git a/Images/PMS_08_Display_All_Contacts.png b/Images/PMS_08_Display_All_Contacts.png
deleted file mode 100644
index 4cb60ef..0000000
Binary files a/Images/PMS_08_Display_All_Contacts.png and /dev/null differ
diff --git a/Images/PMS_09_SeachByName.png b/Images/PMS_09_SeachByName.png
new file mode 100644
index 0000000..76671b1
Binary files /dev/null and b/Images/PMS_09_SeachByName.png differ
diff --git a/Images/PMS_09_Search_By_Name.png b/Images/PMS_09_Search_By_Name.png
deleted file mode 100644
index 08eb0e6..0000000
Binary files a/Images/PMS_09_Search_By_Name.png and /dev/null differ
diff --git a/Images/PMS_10_SearchByNumber.png b/Images/PMS_10_SearchByNumber.png
new file mode 100644
index 0000000..882b9ab
Binary files /dev/null and b/Images/PMS_10_SearchByNumber.png differ
diff --git a/Images/PMS_10_Search_By_Number.png b/Images/PMS_10_Search_By_Number.png
deleted file mode 100644
index 95018b8..0000000
Binary files a/Images/PMS_10_Search_By_Number.png and /dev/null differ
diff --git a/Images/PMS_11_Delete_Contact.png b/Images/PMS_11_Delete_Contact.png
deleted file mode 100644
index 7cbbab5..0000000
Binary files a/Images/PMS_11_Delete_Contact.png and /dev/null differ
diff --git a/Images/PMS_11_SearchByCityName.png b/Images/PMS_11_SearchByCityName.png
new file mode 100644
index 0000000..91c0898
Binary files /dev/null and b/Images/PMS_11_SearchByCityName.png differ
diff --git a/Images/PMS_12_DeleteContact.png b/Images/PMS_12_DeleteContact.png
new file mode 100644
index 0000000..ed0324c
Binary files /dev/null and b/Images/PMS_12_DeleteContact.png differ
diff --git a/Images/PMS_12_Delete_All_Contact.png b/Images/PMS_12_Delete_All_Contact.png
deleted file mode 100644
index 40aecd3..0000000
Binary files a/Images/PMS_12_Delete_All_Contact.png and /dev/null differ
diff --git a/Images/PMS_13_DeleteAllContacts.png b/Images/PMS_13_DeleteAllContacts.png
new file mode 100644
index 0000000..afe04a6
Binary files /dev/null and b/Images/PMS_13_DeleteAllContacts.png differ
diff --git a/Images/PMS_14_NoContactError.png b/Images/PMS_14_NoContactError.png
new file mode 100644
index 0000000..dd4f2fb
Binary files /dev/null and b/Images/PMS_14_NoContactError.png differ
diff --git a/Images/PMS_15_ExitScreen.png b/Images/PMS_15_ExitScreen.png
new file mode 100644
index 0000000..668e33d
Binary files /dev/null and b/Images/PMS_15_ExitScreen.png differ
diff --git a/README.md b/README.md
index 4c721b2..f83efdf 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ Phonebook Management System in the C programming language is a software applicat
 ## Description
 
 You can learn the fundamentals of functions, file handling, and data 
-structure by working on the Phonebook Management System mini-project. 
+structure by working on the Phonebook Management System. 
 This system will show you how to add, list, change or edit, search for, and 
 remove data from/to a file. The functions that make up this project's menu 
 include adding new records, listing them, editing and updating them, looking 
@@ -14,11 +14,11 @@ for saved contacts, and deleting phonebook entries.
 
 ## Documents 
 
-- Synopsis report [here](/Documents/PhonebookManagementSystem_Synopsis.pdf)
-- Use case diagram [here](/Documents/PhonebookManagementSystem_UseCaseDiagram.pdf)
+- Synopsis report [here](/Documents/PhonebookManagementSystem_Synopsis.pdf "Synopsis Report")
+- Use case diagram [here](/Documents/PhonebookManagementSystem_UseCaseDiagram.pdf "Use Case Diagram")
 - Output Images [here](/Images/)
 
-**Note:** If the documents are not rendering on github please download the repository [here](https://github.com/Alkaison/Phonebook-Management-System/archive/refs/heads/main.zip). 
+**Note:** If the documents are not rendering on github please download the repository [here](https://github.com/Alkaison/Phonebook-Management-System/archive/refs/heads/main.zip "Latest Code"). 
 
 ## Features 
 
@@ -28,11 +28,14 @@ We have used many functions in this project. These functions are very easy to un
 - Secure Password Login
 - Admin Panel
 - User Panel
+- Unique phone numbers
+- Advance validation function for user input 
 - Add New Contact
 - Update Contact
 - Display All Contact
 - Search By Name
 - Search By Number
+- Search By City 
 - Delete Contact
 - Delete All Contact
 
@@ -42,59 +45,79 @@ We have used many functions in this project. These functions are very easy to un
 
 - A software (IDE) for reviewing the code
 - C/C++ compiler (Recommended: GCC Compiler)
-- Command Prompt or Windows Powershell
+- Command Prompt or Windows Powershell 
 
 **Note:** This program won't run on online compilers as they don't provide libraries for FILE Management & external storing.
 
+## Contributing 
+
+- If you wish to contribute a new function or want to improve the code quality, you are welcome for your contributions. 
+
+- Fork the repository & make changes, after completion open pull request.
+
+- Thanks in advance 💛 
+
 ## Screenshots 🖼️
 
-### 01. Information Page
+### 01. Introduction Screen 
 
-![Information Page](https://i.ibb.co/T8thjdf/PMS-01-Information-Page.png)
+![Information Page](https://i.ibb.co/rktHD2C/PMS-01-Introduction-Screen.png)
 
-### 02. Login Page
+### 02. Login Screen 
 
-![Login Page](https://i.ibb.co/BfqPzCL/PMS-02-Login-Page.png)
+![Login Page](https://i.ibb.co/vYn8Fnm/PMS-02-Login-Screen.png)
 
 ### 03. Secure Password Login
 
-![Secure Password Login](https://i.ibb.co/kJT6R4J/PMS-03-Secure-Password.png)
+![Secure Password Login](https://i.ibb.co/KzPmpFF/PMS-03-Admin-Login-Secure.png)
 
 ### 04. Admin Panel
 
-![Admin Panel](https://i.ibb.co/BNP4Rns/PMS-04-Admin-Panel.png)
+![Admin Panel](https://i.ibb.co/Fb0gfXv/PMS-04-Admin-Panel.png)
 
 ### 05. User Panel
 
-![User Panel](https://i.ibb.co/FqZ35cm/PMS-05-User-Panel.png)
+![User Panel](https://i.ibb.co/743mZbx/PMS-05-User-Panel.png)
 
 ### 06. Add New Contact
 
-![Add New Contact](https://i.ibb.co/nfR06x6/PMS-06-Add-New-Contact.png)
+![Add New Contact](https://i.ibb.co/YtvXhJs/PMS-06-Add-New-Contact.png)
 
 ### 07. Update Contact
 
-![Update Contact](https://i.ibb.co/vkh7bYF/PMS-07-Update-Contact.png)
+![Update Contact](https://i.ibb.co/vvvXRhh/PMS-07-Update-Contact.png)
 
 ### 08. Display All Contact
 
-![Display All Contact](https://i.ibb.co/vJCXBsw/PMS-08-Display-All-Contacts.png)
+![Display All Contact](https://i.ibb.co/p2x9cvx/PMS-08-Display-All-Contacts.png)
 
 ### 09. Search By Name
 
-![Search By Name](https://i.ibb.co/CtvLXSH/PMS-09-Search-By-Name.png)
+![Search By Name](https://i.ibb.co/3MGKWmn/PMS-09-Seach-By-Name.png)
 
 ### 10. Search By Number
 
-![Search By Number](https://i.ibb.co/WsRSZjK/PMS-10-Search-By-Number.png)
+![Search By Number](https://i.ibb.co/0tL532S/PMS-10-Search-By-Number.png)
+
+### 11. Search By City Name 
+
+![Search By City Name](https://i.ibb.co/hyXZMhd/PMS-11-Search-By-City-Name.png)
+
+### 12. Delete Contact
+
+![Delete Contact](https://i.ibb.co/6DYFThb/PMS-12-Delete-Contact.png)
+
+### 13. Delete All Contact
+
+![Delete All Contact](https://i.ibb.co/BP5CdYT/PMS-13-Delete-All-Contacts.png)
 
-### 11. Delete Contact
+### 14. No Contacts Error 
 
-![Delete Contact](https://i.ibb.co/1zzcpcQ/PMS-11-Delete-Contact.png)
+![No Contacts Error](https://i.ibb.co/LSzLfZ8/PMS-14-No-Contact-Error.png)
 
-### 12. Delete All Contact
+### 15. Exit Screen 
 
-![Delete All Contact](https://i.ibb.co/Smbmhb9/PMS-12-Delete-All-Contact.png)
+![Exit Screen](https://i.ibb.co/N3z5qqM/PMS-15-Exit-Screen.png)
 
 ## MIT LICENSE 📔