Chat (also known as instant messaging) is a form of real-time communication. When you use chat, your message gets delivered to the person on the other end almost instantly, even if the other person is all the way on the other side of the world. The speed with which chat allows communication has made it a popular form of online interaction. Originally, chat programs allowed communication only through text entered in a chat window. As high speed internet access has gained in popularity, chat programs have adapted to include voice and video chat capabilities that take advantage of the bandwidth provided by a high speed connection. You can even chat using text and voice or video simultaneously in most chat programs.
To get started with chat, all you need is access to an internet connection. If you are only using text chat, a dial-up connection will suffice. However, if you want to use the more advanced features of your chat program, such as voice or video chat, you will need to have a high speed connection for the best performance. Video chat in particular requires a lot of bandwidth if you want smooth transfer. Otherwise, frames are dropped and your video looks choppy.
To participate in voice and video chat you may have to purchase additional equipment. For voice chat, you can probably use the microphone built into your computer if you are using a laptop. If you are using a desktop, you may have to buy an external microphone (on many Macs you need to purchase a microphone with a USB connector, as they do not have line-in jacks). Better yet, you may want to buy a headset that includes a microphone. Headsets often provide better sound quality for voice chat, and they also provide some privacy because you can listen to the person on the other end through the headphones instead of your speakers.
Once you have all your equipment connected and ready to go, you can launch iChat, the chat program included with OS X. iChat allows you to chat over three different chat services. You can use your .Mac account, an AOL Instant Messenger (AIM) account, or a Jabber account (Jabber is the protocol used by GoogleTalk, a messaging service provided by Google). You can also use iChat to chat with people on your local area network using the Bonjour protocol built into OS X. iChat supports voice and video chat in addition to text chat.