Small talk is polite conversation that people have with people that they are not very close to. In many English-speaking cultures, it is considered strange or rude not to talk to someone that you know if you are near each other for more than a half minute or so.
Common examples of small talk include:
* Greetings ("Hi." "How are you doing?" "What's up?",etc.)
* Asking about someone's family ("How's Alice?" "How are your kids?")
* Talking about the weather ("It's beautiful today, isn't it?")
* Talking about people you both know ("Have you talked to Jessica lately?" "I saw Barry a couple days ago.")
One guide for engaging in polite small talk is to 1) answer the person's question, 2) give a little extra detail, and then 3)ask another question back:
A: How's your wife doing?
B: Pretty good (1). She's started going to the gym a lot more than she used to (2).
A: Oh yeah? That's good.
B: Yeah, she's enjoying it. What about your wife (3)?
People often engage in small talk whenever they haven't seen each other for more than a few days. Even business calls and meetings often start with a minute or two of small talk.
By the way, you should also know that a lot of people don't like small talk. Some people try not to do it, but those people can be seen as rude.
