Social networking giant Twitter recently raised eyebrows, and caused its stock price to continue falling, by parting ways with four key executives. Leaving were the top executives for products, engineering, human resources, and media partnerships.

This follows the recent layoff off of more than 300 employees, or about 8% of Twitter’s workforce. Since the company’s founding in March 2006 and the launch of the service in July 2006, it has yet to turn a profit despite having more than 300 million active users worldwide.

Twitter’s claim to fame is the 140-character limit of its messages. This allows for the communication, in the words of Twitter co-founder and current CEO Jack Dorsey, of “a short burst of inconsequential information.” Twitter’s famous 140 characters translate into about 30 words or two relatively short sentences. Or four sentence fragments. Twitter is thus sometimes called a microblogging service.

The character limit is both a strength and weakness. When using Twitter you’re forced to be succinct. But you may need to be superficial as well. In announcing the recent management shakeup, Dorsey tweeted not his words as text but an image of his words, since he needed well more than 140 characters.

Twitter’s terminology has become commonplace. Twitter’s messages are “tweets,” and sending one is “tweeting.” If you subscribe to people’s updates, you “follow” them. A “hashtag” is a way to mark keywords or topics in a tweet. A “trend” is hashtag-driven topic that has become popular, or is “trending.”

Whether you love or hate Twitter or are largely indifferent, it’s undeniable that Twitter is a phenomenon. It exploded exponentially in popularity in the years after its launch and soon became a bona fide societal force worldwide.

Twitter was instrumental in helping organize the Arab Spring of 2011, the U.S. Occupy movement, and various other social protests around the world. Boston police tweeted news of the arrest of Boston Marathon bomber Dzhokhar Tsarnaev. The Islamic State group, also called ISIS or ISIL, uses it. Twitter is banned in China, North Korea, and Iran and has been periodically blocked in Egypt, Iraq, Turkey, and Venezuela.

The service is well suited for popular culture. When pop singer Michael Jackson died in 2009, so many tweets went out that Twitter servers temporarily crashed.

Currently, according to Twitter Counter, the Twitter accounts with the most followers are Katy Perry with 80 million, Justin Bieber with 73 million, and Taylor Swift with 69 million. But politicians, business people, scientists, journalists, and others from many walks of life are popular too. President Barack Obama is in fourth place, according to Twitter Counter, with 68 million followers.

Not everybody is enamored with the Twitter phenomenon. It can contribute to narcissism, with tweeters feeling that everybody is waiting breathlessly to read about their every thought or experience. It can inhibit social development in the real world, with online contacts so easy to come by. It can sap productivity at work or school, with tweets an ever-present temptation. Similar criticisms are levied at other social media networks.

Twitter having 320 million active users sounds impressive, but this pales in comparison with its largest competition, Facebook, which has 1.5 billion active users. Other competitors in the U.S. include LinkedIn and Instagram.

Facebook is the most versatile of the four, with the widest scope of services. LinkedIn is the most business oriented. Instagram is focused on photos and short videos.

Twitter’s growth has slowed over the past 18 months, and a big concern of investors and analysts is that as it is currently constructed it may have largely tapped out its potential market.

To try to turn things around, Twitter has been or is considering adding various features and tweaking existing ones. “Moments” compiles photos, video, and messages about news events. You can now broadcast live video from GoPro with the help of Twitter’s Periscope app. But neither appears to have much potential for being huge successes.

Twitter consequently is also thinking about the unthinkable, in the minds of Twitter purists. It may expand the length restrictions on tweets beyond the 140-character limit that has defined the service since its inception. Comments made by Dorsey have fueled speculation that Twitter will increase the maximum length of tweets to 10,000 characters. That’s about 2,000 words, or nearly three times the length of this article.

Twitter has its challenges ahead. But its millions of users remain a formidable force. It isn’t expected to disappear in the foreseeable future. Over the coming months, however, it may change significantly.