You can send text messages (SMS) of up to 160 characters to another mobile phone. If you type more than the allotted text amount (up to 7 pages of 153 characters), the message is delivered as a series of messages (EMS). If you keep typing after the limit, your message is delivered as Multimedia messages (MMS).
Multimedia messages (MMS) can contain text and a picture, location, a recorded voice, an audio file, a video, or a picture slideshow.
The Messaging application automatically converts a message into a multimedia message if you add a subject or attach a media file.