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.
Texting (sometimes called text messaging or wireless messaging) is sending short text messages between cell phones, pagers or other handheld devices. Messages are sent through SMS (short message service). Users can also send text messages from a computer to a handheld device. Web texting, as it's called, is made possible by Web sites called SMS gateways. Download this free guide.