diff --git a/lesson21/hello/CMakeLists.txt b/lesson21/hello/CMakeLists.txt
new file mode 100644
index 0000000..963f0a3
--- /dev/null
+++ b/lesson21/hello/CMakeLists.txt
@@ -0,0 +1,13 @@
+cmake_minimum_required(VERSION 3.15)
+project(hello CXX)
+
+
+
+
+add_library(hello src/hello.cpp)
+target_include_directories(hello PUBLIC include)
+
+
+
+set_target_properties(hello PROPERTIES PUBLIC_HEADER "include/hello.h")
+install(TARGETS hello)
diff --git a/lesson21/hello/conanfile.py b/lesson21/hello/conanfile.py
new file mode 100644
index 0000000..e3c1b88
--- /dev/null
+++ b/lesson21/hello/conanfile.py
@@ -0,0 +1,55 @@
+from conan import ConanFile
+from conan.tools.cmake import CMakeToolchain, CMake, cmake_layout, CMakeDeps
+
+
+class helloRecipe(ConanFile):
+    name = "hello"
+    version = "1.0"
+    package_type = "library"
+
+    # Optional metadata
+    license = "<Put the package license here>"
+    author = "<Put your name here> <And your email here>"
+    url = "<Package recipe repository url here, for issues about the package>"
+    description = "<Description of hello package here>"
+    topics = ("<Put some tag here>", "<here>", "<and here>")
+
+    # Binary configuration
+    settings = "os", "compiler", "build_type", "arch"
+    options = {"shared": [True, False], "fPIC": [True, False]}
+    default_options = {"shared": False, "fPIC": True}
+
+    # Sources are located in the same place as this recipe, copy them to the recipe
+    exports_sources = "CMakeLists.txt", "src/*", "include/*"
+
+    def config_options(self):
+        if self.settings.os == "Windows":
+            self.options.rm_safe("fPIC")
+
+    def configure(self):
+        if self.options.shared:
+            self.options.rm_safe("fPIC")
+
+    def requirements(self):
+        self.requires("fmt/[>=11.0 <12]")
+
+    def layout(self):
+        cmake_layout(self)
+
+    def generate(self):
+        deps = CMakeDeps(self)
+        deps.generate()
+        tc = CMakeToolchain(self)
+        tc.generate()
+
+    def build(self):
+        cmake = CMake(self)
+        cmake.configure()
+        cmake.build()
+
+    def package(self):
+        cmake = CMake(self)
+        cmake.install()
+
+    def package_info(self):
+        self.cpp_info.libs = ["hello"]
diff --git a/lesson21/hello/include/hello.h b/lesson21/hello/include/hello.h
new file mode 100644
index 0000000..b9e261c
--- /dev/null
+++ b/lesson21/hello/include/hello.h
@@ -0,0 +1,14 @@
+#pragma once
+
+#include <vector>
+#include <string>
+
+
+#ifdef _WIN32
+  #define HELLO_EXPORT __declspec(dllexport)
+#else
+  #define HELLO_EXPORT
+#endif
+
+HELLO_EXPORT void hello();
+HELLO_EXPORT void hello_print_vector(const std::vector<std::string> &strings);
diff --git a/lesson21/hello/src/hello.cpp b/lesson21/hello/src/hello.cpp
new file mode 100644
index 0000000..392974d
--- /dev/null
+++ b/lesson21/hello/src/hello.cpp
@@ -0,0 +1,120 @@
+#include <iostream>
+#include "hello.h"
+
+
+
+void hello(){
+    
+
+    #ifdef NDEBUG
+    std::cout << "hello/1.0: Hello World Release!\n";
+    #else
+    std::cout << "hello/1.0: Hello World Debug!\n";
+    #endif
+
+    // ARCHITECTURES
+    #ifdef _M_X64
+    std::cout << "  hello/1.0: _M_X64 defined\n";
+    #endif
+
+    #ifdef _M_IX86
+    std::cout << "  hello/1.0: _M_IX86 defined\n";
+    #endif
+
+    #ifdef _M_ARM64
+    std::cout << "  hello/1.0: _M_ARM64 defined\n";
+    #endif
+
+    #if __i386__
+    std::cout << "  hello/1.0: __i386__ defined\n";
+    #endif
+
+    #if __x86_64__
+    std::cout << "  hello/1.0: __x86_64__ defined\n";
+    #endif
+
+    #if __aarch64__
+    std::cout << "  hello/1.0: __aarch64__ defined\n";
+    #endif
+
+    // Libstdc++
+    #if defined _GLIBCXX_USE_CXX11_ABI
+    std::cout << "  hello/1.0: _GLIBCXX_USE_CXX11_ABI "<< _GLIBCXX_USE_CXX11_ABI << "\n";
+    #endif
+
+    // MSVC runtime
+    #if defined(_DEBUG)
+        #if defined(_MT) && defined(_DLL)
+        std::cout << "  hello/1.0: MSVC runtime: MultiThreadedDebugDLL\n";
+        #elif defined(_MT)
+        std::cout << "  hello/1.0: MSVC runtime: MultiThreadedDebug\n";
+        #endif
+    #else
+        #if defined(_MT) && defined(_DLL)
+        std::cout << "  hello/1.0: MSVC runtime: MultiThreadedDLL\n";
+        #elif defined(_MT)
+        std::cout << "  hello/1.0: MSVC runtime: MultiThreaded\n";
+        #endif
+    #endif
+
+    // COMPILER VERSIONS
+    #if _MSC_VER
+    std::cout << "  hello/1.0: _MSC_VER" << _MSC_VER<< "\n";
+    #endif
+
+    #if _MSVC_LANG
+    std::cout << "  hello/1.0: _MSVC_LANG" << _MSVC_LANG<< "\n";
+    #endif
+
+    #if __cplusplus
+    std::cout << "  hello/1.0: __cplusplus" << __cplusplus<< "\n";
+    #endif
+
+    #if __INTEL_COMPILER
+    std::cout << "  hello/1.0: __INTEL_COMPILER" << __INTEL_COMPILER<< "\n";
+    #endif
+
+    #if __GNUC__
+    std::cout << "  hello/1.0: __GNUC__" << __GNUC__<< "\n";
+    #endif
+
+    #if __GNUC_MINOR__
+    std::cout << "  hello/1.0: __GNUC_MINOR__" << __GNUC_MINOR__<< "\n";
+    #endif
+
+    #if __clang_major__
+    std::cout << "  hello/1.0: __clang_major__" << __clang_major__<< "\n";
+    #endif
+
+    #if __clang_minor__
+    std::cout << "  hello/1.0: __clang_minor__" << __clang_minor__<< "\n";
+    #endif
+
+    #if __apple_build_version__
+    std::cout << "  hello/1.0: __apple_build_version__" << __apple_build_version__<< "\n";
+    #endif
+
+    // SUBSYSTEMS
+
+    #if __MSYS__
+    std::cout << "  hello/1.0: __MSYS__" << __MSYS__<< "\n";
+    #endif
+
+    #if __MINGW32__
+    std::cout << "  hello/1.0: __MINGW32__" << __MINGW32__<< "\n";
+    #endif
+
+    #if __MINGW64__
+    std::cout << "  hello/1.0: __MINGW64__" << __MINGW64__<< "\n";
+    #endif
+
+    #if __CYGWIN__
+    std::cout << "  hello/1.0: __CYGWIN__" << __CYGWIN__<< "\n";
+    #endif
+}
+
+void hello_print_vector(const std::vector<std::string> &strings) {
+    for(std::vector<std::string>::const_iterator it = strings.begin(); it != strings.end(); ++it) {
+        std::cout << "hello/1.0 " << *it << std::endl;
+    }
+}
diff --git a/lesson21/hello/test_package/CMakeLists.txt b/lesson21/hello/test_package/CMakeLists.txt
new file mode 100644
index 0000000..c33c2a7
--- /dev/null
+++ b/lesson21/hello/test_package/CMakeLists.txt
@@ -0,0 +1,7 @@
+cmake_minimum_required(VERSION 3.15)
+project(PackageTest CXX)
+
+find_package(hello CONFIG REQUIRED)
+
+add_executable(example src/example.cpp)
+target_link_libraries(example hello::hello)
diff --git a/lesson21/hello/test_package/conanfile.py b/lesson21/hello/test_package/conanfile.py
new file mode 100644
index 0000000..e073113
--- /dev/null
+++ b/lesson21/hello/test_package/conanfile.py
@@ -0,0 +1,26 @@
+import os
+
+from conan import ConanFile
+from conan.tools.cmake import CMake, cmake_layout
+from conan.tools.build import can_run
+
+
+class helloTestConan(ConanFile):
+    settings = "os", "compiler", "build_type", "arch"
+    generators = "CMakeDeps", "CMakeToolchain"
+
+    def requirements(self):
+        self.requires(self.tested_reference_str)
+
+    def build(self):
+        cmake = CMake(self)
+        cmake.configure()
+        cmake.build()
+
+    def layout(self):
+        cmake_layout(self)
+
+    def test(self):
+        if can_run(self):
+            cmd = os.path.join(self.cpp.build.bindir, "example")
+            self.run(cmd, env="conanrun")
diff --git a/lesson21/hello/test_package/src/example.cpp b/lesson21/hello/test_package/src/example.cpp
new file mode 100644
index 0000000..f6acdb3
--- /dev/null
+++ b/lesson21/hello/test_package/src/example.cpp
@@ -0,0 +1,12 @@
+#include "hello.h"
+#include <vector>
+#include <string>
+
+int main() {
+    hello();
+
+    std::vector<std::string> vec;
+    vec.push_back("test_package");
+
+    hello_print_vector(vec);
+}
diff --git a/lesson21/test.ps1 b/lesson21/test.ps1
new file mode 100644
index 0000000..674b0dc
--- /dev/null
+++ b/lesson21/test.ps1
@@ -0,0 +1,2 @@
+$ErrorActionPreference = 'Stop'
+
diff --git a/lesson21/test.sh b/lesson21/test.sh
new file mode 100755
index 0000000..94ef7de
--- /dev/null
+++ b/lesson21/test.sh
@@ -0,0 +1,4 @@
+#!/bin/bash
+
+set -e
+