Both the short message service -- often called texting -- and Twitter are methods for communicating small messages. Posts on Twitter can contain up to 140 characters, while SMS texts can have 160. Other than their short length, however, the two services differ significantly in use, cost and scope. In general, texts only go to a single recipient, while tweets on Twitter are visible to the public.
How Texting Works
Texting is a method for sending messages from one cell phone to another. Most phones -- both traditional cell phones and smartphones -- can send and receive texts. Cell phone carriers bill texting separately from your calls, often charging per-text. You can also subscribe to plans that allow a certain number of texts per month for a flat fee.
How Twitter Works
Like with texting, you can use Twitter to send private messages, but the service primarily focuses on social sharing. By default, anyone online can potentially see your tweets. People who choose to follow you will automatically see your messages on their Twitter home page, and those you follow will appear on your home page. Unlike some other social media sites, you can follow anyone you want on Twitter, even if you don't know them personally.
Ways to Use Twitter
Unlike texting, you can send and read tweets from many different devices using the same account. On your computer, you can visit Twitter's website to write messages and find other users' posts. Twitter makes smartphone apps for iPhone, Android, Windows Phone, Blackberry and many other mobile systems that allow you to write and read tweets. Other developers also make both desktop and mobile applications that tie into Twitter -- for example, some games can automatically send tweets when you earn achievements.
If you want to update or read Twitter from your phone, but don't have a smartphone that supports the Twitter app, you can send and receive updates via text message. To link your account, text "START" to 40404 and follow the directions to log in. Although Twitter does not cost anything, texted tweets will count against your texting plan. To use fewer texts, you can opt to only send tweets by text, but not receive any.