Stands for "Multimedia Messaging Service." MMS is mobile phone service that allows users to send multimedia messages to each other. This includes images, videos, and sound files.
MMS is an extension of SMS, which is used to send and receive text messages. Like text messages, multimedia messages are first transmitted to a central server maintained by the cellular service provider. Once the message has been received by the server, it is forwarded to the recipient. If the recipient's phone is off or she does not have cell phone service when the message is sent, the server will hold the message and send it once the recipient's phone is available.
Most modern cell phones and smartphones support MMS messaging. MMS support is typically integrated into the text messaging interface and activates automatically when needed. For example, if you type a text-only message, it will be sent using SMS. If you add a graphic or video, the multimedia portion will be transmitted via MMS. Similarly, if someone sends you an multimedia message, your phone will automatically use MMS to receive the file. If your phone does not support MMS messages, you will most likely receive a text message that includes a URL where you can view the file from a Web browser.