Secret
From Wikipedia, a free encyclopedia written in simple English for easy reading.
A secret is a piece of information that one person or a group of people know, and do not want others, either everyone or certain people to know.
There are many reasons for keeping secrets. Some secrets are good (ones that should be kept secret), others are bad (ones that ought not to be kept secret). Some things will only be kept secret until a certain time. Other things may be kept secret for ever.
Secrets can be fun to keep: a present that you are going to give someone, or a surprise party that you are organizing for someone.
Sometimes things might be kept secret from someone because you (or a group of people) feel it would upset them unnecessarily.
Some things need to be kept secret for security reasons. If you have a bank account you must keep your PIN number secret. No one else should know it.
In businesses a lot of information is kept secret. This is usually called confidential. Things that are talked about at meetings are sometimes confidential. People who were at the meeting should not go telling everyone else what was discussed.
Sometimes there are things that ought not to be kept secret. This might be the case if you or someone else has done something wrong. If you are uncomfortable about a secret it may be better to tell someone about it.