The concept isn't new, of course (the sites themselves have anticpated post-death needs for years), and it has its fair share of critics. After all, it takes just a few seconds to send your condolences. Unless people write detailed stories, it's hard to know whether they're genuinely sad or just paying a token amount of respect. There's certainly a case to be made for keeping some grief offline, since there are likely far fewer people who can relate to losing one of your close family members than there are for a rock star.

However, the rapid rise of internet-based mourning (especially in the past several weeks) suggests that people have wanted this public outlet for a while. It's just that technology and cultural norms have shifted enough to make it viable -- you can post that Twitter tribute or YouTube response knowing that there will be plenty of people who can see and share what you're going through. You probably won't see formal online grieving periods any time soon, but you also won't be left wondering if your friends and acquaintances miss a celebrity as much as you do.

[Image credit: Xinhua/Han Yan via Getty Images]