Find them on Facebook and Twitter!--as if these two are the Coke and the Pepsi of the social networking world. More like the Coke and the 7UP, actually. Google trends on searches for the terms "facebook" and "twitter", respectively, with "youtube" added in for additional perspective:
Over half of all US adults have Facebook accounts. By contrast, just 1-in-9 use Twitter.
Perhaps Twitter is the new Facebook? Twitter is seven years old. In human years, that constitutes youth. The virtual world's aging process has more in common with dog years, though. Twitter isn't novel.
Facebook's IPO was underwhelming (for outside investors, not so much for the company itself). Twitter's was great (for those looking in from the outside; the company left billions on the table). Twitter, however, doesn't have a larger market presence as a consequence. To the contrary, Facebook's market cap is more than four times Twitter's.
Twitter isn't a high-brow version of the proletariat's Facebook, either. From Pew Research last year:
Heavily urban, heavily NAM. Twitter is certainly hip. And it's convenient for lazy, cash-strapped media outlets that are able to replace something approaching actual journalism by simply copying a celebrity's half-sentence tweet and passing it off as newsworthy.
What else should be expected from a platform with such space constraints that users might as well be limited to rap's contemporary lexicon, though?
Pew doesn't break down the racial characteristics of Facebook users, but unlike Twitter, Facebook usage increases with education and income, so it's presumably icier than Twitter's sunny profile.
To Twitter's tweeting there is Facebook's essentially identical status updating. To Twitter's re-tweeting there is Facebook's essentially identically sharing. That basically summarizes everything Twitter does. As noted, Facebook does the same (with wider reach), but only in addition to about a bazillion other things to help its far more numerous users navel gaze or whittle time away candy crushing it.
Parenthetical disclosure: I have no employment or shareholder connections to either company, I find Mark Zuckerberg's open borders advocacy more obnoxious than Jack Dorsey's standard but not especially agitating SWPL tendencies, and I have user accounts on both sites.