A sock puppet is a second account pretending to be a different person for the purpose of building credibility where no other real members give that credibilty.

Looking up some difintions you see phrases like this:
1. It is typically used to say good things about oneself while pretending to be somebody else,
2. They are typically used for block evasion, creating false majority opinions, vote stacking, and other similar pursuits.
3. Multiple accounts controlled by the same user can dominate comment forums and spread fake news.

Examples on the gambling forums would be Rob Singer's Jerry Logan, or on this Forum Rob Singer's GirlFriday used to support his opinion that AP's can't get a mortgage when most do. Moses also created a sock puppet account here pretending to be his girlfriend and on other forums pretending to be a friend "tater". Those are sockpuppets.

Examples of multiple accounts that aren't really sockpuppets are 1. Garnabby/bill young and all his accounts and 2. Tasha and most of her accounts. These are just weird multiple accounts, because there is no intent to deceive anyone. Just some strange need to have multiple identities.

I have never created an account trying to deceive anyone or pretend I was someone else, which is what a sock puppet is. I create accounts where I can't post as Kewlj or KJ to say something I want to say. Not only do I not hide who I really am, but I often use something that makes it obvious, knowing I will be banned. because the purpose isn't to deceive anyone, just to say what I want to say. And that will not stop. If I have something to say, I will say it.