People use slang so that other people won't know what they're talking about.
This can be a microscopic biological component, a holding area for prisoners, or slang for a cell phone.
William K. Bentley has written: 'Prison slang' -- subject(s): Americanisms, Dictionaries, English language, Language, Prisoners, Prisons, Slang, Terminology
You use slang in casual conversation, especially with friends.
The prisoners were sentanced by the severity of their crimes.
Everybody uses slang.
Everyone uses slang. Name any famous person -- yes, they use slang, too.
Yes, in an informal letter it is OK to use slang.
Writers use slang because real people use it.
All of them. Everyone uses slang at some time.
when we know each other very well with the same interest informally, it is appropriate to use slang.
you use the computer
100%. Everyone in the world uses slang.