What language and data structures does MYSQL uses as backend? I am just curious to know what data structures and languages does MYSQL exactly use as back end language? and what does the file format .MYD , .MYI and .frm stand for and how does MYSQL use them?

Thanks.
MySQL can be compiled in C/C++ and you can download the source code to do so.

At this link, Under the Select Platform ComboBox, Select Source Code and Download it from there

The .frm , .MYD, and .MYI make up a MyISAM table

For example, the user table for the mysql grants is amde up of three files


/var/lib/mysql/mysql/user.frm (Table Structure for any Storage Engine)
/var/lib/mysql/mysql/user.MYD (MyISAM Table Data)
/var/lib/mysql/mysql/user.MYI (MyISAM Table Indexes)