lock (thing)

There seem to be basically two types of locks:

Type 1: Locks whose key is a tangible object

Advantages:

• You pretty much know whether or not another person has possession of your key. (Although, someone might steal your key, make a copy and then return the original.)
• If you have a poor head for rote memorization, this is the type of lock for you.

Disadvantages:

• If you forget ONCE to bring the key with you, you're screwed.

Type 2: Locks whose key is a piece of information

Advantages:

• Memorize your key well, and you will never lose it.
• You have less things to keep track of, as you never ask "where the hell are my keys?"
• No one can steal your key (except if they trick or force it out of you).
• Of the two types of lock, this type tends to be quicker and easier to operate.

Disadvantages:

• Mumble to yourself once, or let someone look too close, and sayonara, security!!
• These can be easy to forget. And don't you dare pick your daughter's birthday for a combination.

NOTE: Some people, having a Type 2 lock, write down the combination, turning it into a lock with most of the worst aspects of Type 1 AND Type 2 locks.