Twitter is both a microblogging site and a social network. On Twitter, users communicate using tweets, short text excerpts which can contain links and media items. Users can both tweet and read tweets from other accounts, with various options to choose which tweets you see. Twitter user can send tweets to other users, mention other users and "retweet" other users' tweets. Although Twitter is relatively simple to use for basic tasks, the service offers a lot of potential complexity in how you choose to use it.
The medium of communication used on Twitter is called a "tweet." A tweet is a string of text with a maximum length of 140 characters. Tweets can contain links to Web pages, media items such as images and video, plus a range of formatted text items with special functions within Twitter, including hashtags and mentions. Twitter presents tweets within timelines, with the most recent tweets appearing at the top of a timeline. Twitter is accessible via the Web browser or via an application, for example on mobile devices running Android or iOS.
When you sign up for a Twitter account, you can choose which other Twitter users you wish to follow. If you choose to follow a Twitter account, the tweets from that account will appear in your main Twitter timeline. This includes tweets from the users whose accounts you have followed and anything they have retweeted from other accounts. To retweet a tweet means to repeat the tweet in your own tweet timeline, so that your users will see it regardless of whether they follow the account which originally tweeted it. Other Twitter users can follow you as you follow them. If a user follows you on Twitter, they will see your tweets in their timeline.
Twitter provides a variety of ways to communicate with other Twitter users. You can reply to tweets, in which case the tweet text begins with the account name of the user you are replying to, for example: "@google I disagree." You can mention someone in a tweet by including their username preceded by the ampersand character, as at the start of a reply. If you either reply to a tweet or include a username in a tweet to mention the user, they will see notifications of this in the "Connect" section of their account. Similarly, you will see any mentions of your own username under "Connect." You can also send private direct messages to anyone you follow who follows you back.
The "Discover" section in Twitter allows you to navigate recent tweets on various subjects. You can see an overview of subjects being tweeted, with these tailored to topics that are popular among the accounts you follow. You can also see the list of trending topics, which includes those that are currently increasing in popularity. Twitter users include hashtags in their tweets to tweet on a common topic, for example "#summer." This allows you to instantly see whatever is being said on that topic, regardless of whether the tweets are from accounts you follow.