For starters, the acronym and hashtag are references to the "Top Conservatives On Twitter." When used in the hashtag form, as it is most often, the term provides a way for conservatives in particular and Republicans in general to locate and follow the tweets of their like-minded brethren.
And the term is also a reference to an influential list of those so-called top conservatives, which is maintained at the website Top Conservatives on Twitter.
The site provides a rundown of the most-popular conservative Twitter users ordered by the number of followers. The list runs the gamut from top GOP politicians to key right-leaning journalists.
The No. 1 slot is occupied by former U.S. House of Representatives Speaker Newt Gingrich, who is followed by former Republican vice presidential nominee Sarah Palin, radio personality Duane Patterson, Fox News Channel host Sean Hannity, and radio talk-show host Glenn Beck.
Many conservative users of Twitter tag their posts with #TCOT ensure that folks who may be interested in their take on politics will be able to find their tweets.
Rather than having their right-wing musings, news, and observations lost in the ether, conservatives know they can boost the chances that their tweets will be found by other conservatives by including #TCOT in their 140-character dispatches.
Google Trends reported that the acronym and hashtag appear to have cropped up online sometime near the end of 2008, and that it since exploded in popularity, remaining in common use to this day.
An an SFGate.com City Brights Blog contributor looked further into the provenance of the #TCOT movement.
"#TCOT was founded by tea party leader Michael Patrick Leahy and quickly became a force to be reckoned with in the Twitter stream world," Yobie Benjamin wrote.
And apparently there is a progressive version of #TCOT, known as #P2, which Benjamin reported was created by Tweet Progress to bring progressives together on Twitter and provide an alternative to the #TCOT crowd.