This field keeps count of how many consecutive bad logins this user has had. It is used to lock out accounts that are being attacked by password guessers. Each time they enter their password incorrectly, this number will be increased. If it get to the bad login limit (usually 5), they will not be able to log in at all until you reset their count to 0. Each time the user logs in correctly, the count will be reset to 0 automatically. This means that users will be locked out if they enter a bad password 5 times in a row.

If you leave this field blank, then no bad login limits will be applied to this user.