URLs in CodeIgniter are designed to be search-engine and human-friendly. Rather than using the standard “query-string” approach to URLs that is synonymous with dynamic systems, CodeIgniter uses a segment-based approach:

URL :  gophp.in/news/article/my_article

URL Structure:  gophp.in/class/method/ID

Here news is the name of the Controller

article is the method available in a news class

my_article is the parameter to the article method

An URL is the combination of Base URL and Base URI

URL :http://gophp.in/news/article/my_article

Base Url: http://gophp.in

Base URI: /news/article/my_article