Why don't my contacts show up in yahoo mail?

In yahoo mail chat, why are there contacts that show up as online that i dont have on my mail contact list?

• when i sign on to all new mail, at times if someone is online to chat, people show up on my contacts list that i never added to my account. I just want to know how they got there. Some of them do look familiar, just dont know how. Thanks!

• Answer:

  did you add them to your mail list if not then start now { bu be ware of junck!!!!}