Certain characters are not allowed for usernames and passwords. These characters can be used in place of other characters in the password or username. Example: The password "password" can be accessed by typing "pa'sword" or "pass'''d".

The list of invalid characters are as follows:

commas [,]

quotation marks single or double [", ']

question marks [?]

percentage symbols [%]

tildes [~]

pounds [#]

ampersands [&]

at symbols [@]