Today marks microblogging site Twitter's fifth birthday. It has come a long way in five years, with Edison Research reporting that awareness of the site is almost universal among Americans.

According to the official Twitter blog, the company is celebrating several milestones on the fifth anniversary of its launch. It boasts more than 400 full-time employees. It also serves more than 140 million Tweets per day. (Brafton recently reported on the company's rapidly growing user base, which helps marketers reach a broad audience.)

Additionally, research from Edison shows that 92 percent of Americans above the age of 12 are familiar with the microblogging site. In just five years, it has achieved broad awareness, with Edison experts saying, “it's difficult to see how it could be much higher.”

The majority of growth seems to have occurred between 2009 and 2010, when the site jumped from 26 percent to 87 percent awareness.

Even as the site continues to climb in popularity, social marketers should consider that Facebook still offers access to a much larger audience, with more than 500 million active users. Plus, Brafton recently reported that a study indicates Facebook Likes are linked to higher revenues than Tweets.