聊天(liáo tiān) - to chat, to make small talk in Mandarin

聊天 (liáo tiān) is unhurried, purposeless talk: the conversation you have with a neighbour at the gate or a friend over tea. It is warm rather than trivial, and Chinese does not carry the faint English sneer of "small talk".

Grammatically it is a verb plus its object, which matters more than it sounds. You cannot put another object after it, so "chat with him" is 跟他聊天, never 聊天他. When you want to say how long or how much, the verb repeats around the middle: 聊天聊了两个小时, or in speech simply 聊了两个小时.

The trap is assuming it covers online chat as a noun. The app feature is 聊天 too, and 聊天记录 is a chat log, but the everyday spoken word for messaging someone is usually just 聊 or 发消息. Reach for 聊天 when the picture is two people talking with nothing to achieve.