Great info-graphic of early web, directories and search engines this will help in gaining the number 1 position in SEO. This Info-Graphics give views on requirements, Major Ranking Factors and Most relevant changes and updates.
Hyper Text Transfer Protocol or HTTP response status codes are returned when search engines or website visitors make a request to a web server. These codes with three digit value indicate the response and status of HTTP requests. The http response starts form 1xx, 2xx, 3xx, 4xx and 5xx for 1xx I suggest you to do some search hear I am explaining you the rest of the http status codes.