Take one minute of video. Look at the file size. Now how many of these 1 minute files can you fit onto an 8GB card in your particular format and camera/device.
SMS stands for Short Message Service, which is the formal name for text messaging. It's a way to send short, text-only messages from one phone to another. These messages are usually sent over a cellular data network. That's not always true, though, as in the case of iMessage below.
Text messaging. Text messaging (SMS) is a two-way mobile messaging service that allows you to send and receive short text and email messages on text-capable mobile devices. You can use text messaging with both T-Mobile and non-T-Mobile customers.