This articles demonstrate and explains how to create a secure PHP login script that will allow safe authentication. Here, cookies are not used because of preventive measure against cross-side scripting. The back-end used is MySQL. So, you should have knowledge of MySQL and database as well.

The robots.txt file is a text file that has specific instructions for search engine robots about specific content that they are not allowed to index. These instructions tells search engine about which pages of a website should be indexed.