Facebook Chat enables members to send and receive messages in real-time as though they're chatting in person. To help facilitate the back-and-forth conversational flow, Facebook uses indicators to let you know when someone is typing a message to you.

White Chat Bubbles

When chatting with a Facebook friend, you simply type your message in the appropriate space on your device, send and wait. Once your message is received, your friend can read it and may choose to respond. A white bubble will appear below your message, indicating that she is, in fact, typing her response. These visual cues help to facilitate the flow of your conversation, keeping questions and answers in proper order. Chatting lends itself to terse, fragmentary bits of text, rather than properly formatted sentences. Knowing when someone is typing a response enables you to give him a chance to express himself.