Rumors can be damaging to other's lives, self esteem, and relationships. A participant in gossip is as guilty as the person who started the rumors. People who work in an office environment know all too well how damaging rumors can be. A seemingly small tale, which might actually be 95% true, starts at one end and becomes a tall tale with 95% lies by the time it reaches the top floor.
Help in this type of scenario by not participating - though sometimes it may be difficult because you try to be a nice, polite person. Also, you don't want to seem like an uptight, "too good for the rest of the office" personality. There are, however, many more ways you can influence the wrong-doers to do the right thing.
Avoid discussing it. When someone comes to you with a little story about someone else you can say "I'm sorry, I really can't talk right now, I have so much to do before I leave today." As you get done saying that, pick up the phone and start dialing - maybe you can call IT and ask for help on some PC issue or call someone you meant to call anyway.
Use distraction. Another thing you can do is to pick up some of your folders and mail and start walking towards the mail room or somewhere away from your desk. Give the impression of being in a bit of a rush.
Be forthright. At the first sign of someone who likes to gossip - know who they are and have a plan so that you're not caught off guard - politely say, "I don't think it's fair to talk about Lisa behind her back, maybe we should address this issue with her right now. Let's give her a call." If they say no, then it's likely they'll never be back to tell you any office secrets. If the answer is, "Yes, great," the issue will be resolved.
Keep calm at home too. Stay-at-home/work-from-home moms also have similar situations. In these cases it's more of a neighborhood issue. You live with your neighbors so professionalism is not the issue anymore. You can, however, use the same tactics. If a neighbor comes by to chat about the couple down the street with the cheating husband, etc., simply say, "I don't like to get involved in other people's private lives. I'd rather not know about it," or "It's sad that they are having difficulties. Oh well, it's none of my business. So what are you doing this weekend?" or "Look at the flowers I planted in my garden." Change the topic after making your point.
Avoid rumors as a kid. Rumors aren't always about adults, and many rumors can be aimed at children. If you have a rumor about yourself that is small, do everything in your power to stop it, as it will grow quickly, and you will start to drown in rumors.
Challenge the veracity. Big rumors are the hardest to deal with, as they are not easily stopped. To try to stop them, tell everyone they aren't true. It can be embarrassing, but it will just become worse over time if you do nothing to stop it.
At the first sign of gossip, stop it casually and politely. Be aggressive only if the person continuously persists.
Rumors usually begin with what was a simple truth, and by the time you hear it's most likely a complete lie.
Some rumors are completely childish, especially in elementary/middle school. They can be small and easy to deal with (such as likes someone, namely something like Joe likes Susan) that usually die out, or it can be something big (such as disgusting things, namely something like wears/fills diapers in school). Small ones are easier to deal with, as they can be quickly stopped if you stop whoever is spreading the rumors. The example of Joe likes Susan is easily stopped by talking to Joe/Susan, and stopping them. Big rumors are a lot harder to deal with, as your entire grade/class/school might know them.
If they talk about your neighbors/co-workers, they will talk about you. But keep in mind that you don't have to like everyone. The reverse is also true: not everyone has to like you.
Always be friendly and polite to everyone.