chat 
(chăt)
(chăt)intr.v. chat·ted, chat·ting, chats
1. To converse in an easy, familiar manner; talk lightly and casually.
2. Computers To participate in a synchronous exchange of remarks with one or more people over a computer network.
n.
Phrasal Verb: 1. An informal, light conversation.
2. Computers A synchronous exchange of remarks over a computer network.
3. Any of various birds in the families Muscicapidae or Parulidae that have a chattering call, especially the yellow-breasted chat.
chat up
1. To engage (someone) in light, casual talk: "He would be ... chatting up folks from Kansas" (Vanity Fair).
2. To talk informally with (someone), especially in a flirtatious manner.
[Middle English chatten, to jabber, alteration of chateren; see CHATTER.]