Celebrities, politicians, groups and people of all ages use Twitter. A post on Twitter is commonly known as a tweet and can be comprised of up to 140 characters. You typically tweet comments and links with hashtags, which offset terms to be indexed and searchable, or mentions, which tag other accounts, to get the attention of others. These posts are publicly visible by default and are seen by others in news feeds or through your profile page for a specified amount of time, and limited numbers of them are visible.
Personal Archive
Your personal tweets each have a permalink that search engines and other data harvesting services can index so anyone can find them. Twitter allows you to access of up to 3,200 tweets of a person's timeline, unless you know the permalink and enter it in manually.
Hashtag and Keyword Archive
Twitter restricts you to an archive of 1,500 tweets for a specific hashtag or keyword. To see its archive, type the specific reference into the Twitter search engine to see the tweets that used it. You can use a third-party tool called What The Hashtag (wthashtag.com) to create an archive in HTML Web language format and RSS feed based on a hashtag.
Public Archive
The newest tweets are found at the top of the time line that appears on your Twitter homepage. Twitter initially allowed you to search for tweets as far back as three months, but that range has deceased over time as more people started using Twitter and tying up its resources. Websites like TwapperKeeper archive tweets and analyze the most current trends of the public archive. As of April 19, 2011, TwapperKeeper found Twitter's search limitations allow you to find posts from the last seven to 10 days.
Archiving Services
You can archive your tweets through third-party applications and websites, such as TwapperKeeper (twapperkeeper.com) and TweetDoc (tweetdoc.org). If you have a WordPress account, you can use the Lifestream plug-in to archive your posts by integrating Twitter with your blog. To capture tweets to your computer, use The Archivist Desktop to begin a search and data mining project.
