What is a (#) Hashtag?

Simply put, a hashtag is an easy way for people to categorize, find and join conversations on a particular topic. The hashtag is used to highlight keywords or topics within a Tweet, and can be placed anywhere within a post. Thanks to the member-driven online information site Twitter, the lowly "pound" or "number" symbol "#" has been elevated to a new role. The hash mark, or pound symbol, (#) is now known by social media users as a "hashtag" or "hash tag". Posts that have the same keywords prefixed with the # symbol are grouped together in user searches, bringing a level of order to the frenzied chaotic world of Twitter. Twitter user Chris Messina (@chrismessina) first Tweeted with a hashtag symbol # in August 2007, as a way to define groups on the social media site. The use of the pound symbol to categorize messages and define conversations spread quickly throughout the Twitter community, and is now an integral part of this fast-paced live information network. According to Twitter, in 2011 over 10 percent of all Tweets now contain one or more hashtags. With an average of 140 million Tweets and half a million new accounts created every day, it is easy to see why users need some way of sorting through all these messages.

How Search Twitter Using Hashtags

Any Tweet posted on a public account can be searched by anyone, and posters often use hashtags to help direct searches to their posts. For example, Twitter users can elect to follow all Tweets that include the hashtag #WhiteSox to receive updates about the Chicago White Sox baseball team. Users looking for the best fuel prices can search for #cheapgas and the #osama hashtag was especially popular in May 2011. Posters can include more than one hashtag within a single Tweet, so when searching for posts users can enter multiple hashtag terms, like #NewYork #Pizza.

Creating A Hashtag

Twitter users are free to develop and use their own hashtags as long as they fall within the Twitter rules set out by the company. These rules address issues like offensive and threatening language, as well as impersonating an individual, group or business. Before deciding on a hashtag, users should do some research to see what keywords are available. It's also important to keep hashtags brief, as the words and numbers prefixed with the # symbol are included in the 140-character limit per Tweet. Hashtags should be directly related to the topic. For example, users who want to set up a group for their running group might want to use a hashtag label that includes terms that group members would recognize, like #SFBayRoadrunners. When properly used, Twitter hashtags can be a powerful social media tool for business promotion and trend tracking.

Hashtag Rules and Etiquette

According to The Twitter Rules, Twitter accounts will be deemed to be "spamming" if used to post numerous updates using a # that are unrelated to the hashtag topic or group, resulting in permanent suspension of the offending account. Because hashtags are relatively new, and the Twitter community at large generally dictates what is the norm on the site the acceptable use of hashtags is constantly evolving. The question "what is a hashtag" is an ongoing one among social media users, and the definition of a hashtag continues to evolve. Currently, it is acceptable to tag only significant posts that will contribute to the general conversation with one hashtag. Using two hashtags is acceptable, especially when one of the # tags includes an actual location, such as #SanDiego and #wildfires. According to Wikihow, using three hashtags in one Tweet is the absolute maximum, and doing so risks "raising the ire of the community."