security

It can have two meanings. The most common meaning these days is as follows: Most people use different passwords to log into different things (for example different websites). The problem is that they forget which password for which site and so you can have the computer store all of your different passwords (encrypted) and let you access them using just one 'universal' password. The big security problem is then that if someone steals your universal password then they have access to all of your passwords. (The other older meaning is that everyone using a network uses the same password (universal password) for everything. The security problem here is that there is much more risk of someone revealing the password.)