A retweet or RT is defined as reposting a tweet made by another online user on Twitter. The retweet is indicated by the letters ?RT? found at the start of the message. This should let online users know that the message is not your own but from someone else online.
It is not officially a command on the website although users are advised to use it to acknowledge the original creator of the tweet, especially if you're inserting a comment with the RT. Otherwise, you can simply click the "Retweet" function on the post itself and it will automatically show up on your timeline as a retweet.
Retweets can also be very effective in gaining new followers and driving more traffic to your account or site.
How to Retweet Properly
Start by logging on to Twitter and viewing your account. If you see a message that you?d like to retweet, move the mouse over the message then search for the retweet or RT icon. Click on the icon and you should discover a pop-up window. Click the Retweet button. The message will automatically be visible as your own post but acknowledging the source of the tweet. Using a Twitter client is ideal since others can also put comments and replies to the retweet.