Amazon Product Advertising API for product selection and discovery functionality so that developers can advertise Amazon products to your website.
Amazon_api is library file place it inside application/library/ folder
Edit Amazon_api is library file set config variables with your
$this->load->library('amazon_api'); //load the library amazon_api
$this->amazon_api->searchProducts($search_keyword, $category, $searchType);
eg:$this->amazon_api->searchProducts('X-men','DVD','TITLE');
More categories can be found here: http://docs.amazonwebservices.com/AWSECommerceService/latest/DG/APPNDX_SearchIndexValues.html
http://www.crashcoder.com/codeigniter-php-amazon-product-advertising-api-apaa-library/