while working on a project, I found that "user_pass" column in "wp_users" table is varchar(64). WordPress always stores user password in md5 which is a 32 char ASCII string. So why not store it in char(32) with ascii collation. I am asking because I am working on a table that stores user password. Is there any other advantage of using varchar(64).
It is because of different encrypted algorithm. Sometimes users will override the MD5, which is the default algorithm, and add their own, which might need a little longer length to store the password.
Take a look at the Q&A's »What data type to use for hashed password field and what length?«, having detailed information about hashes and their length, at Stackoverflow for reference.