Why enter password twice?
The double-entry system for passwords is standard and widely used. Therefore, some people believe there's no significant usability harm in continuing to ask for it twice. The purpose is simply to prevent the user from making mistakes.
What is the confirm password?
Whenever a user creates a password, there is always one more field of confirm password. It checks that the password entered by the user is same as this confirm password fields. To create a valid password, both the password and confirm password fields value must be matched.