"Yo." That is all you can say with Yo, the new messaging app for iOS and Android. Yet somehow it has raised $1 million from investors and has attracted 50,000 users. The self-described "single-tap zero character communication tool" was created in eight hours by Or Arbel, an entrepreneur who moved to San Francisco from Israel. (Yes, he is hiring). As one might imagine, it's pretty easy to use. Tap someone's name and it will send a push notification that says, "Yo." The app recently took off — at least on Twitter, where it has become a running joke. No word on whether Arbel is working on a follow-up, "Sup?"

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True story: Yo just has to add picture functionality to make Facebook offer a couple billion for it — Matt O'Brien (@ObsoleteDogma) June 18, 2014

when will taye diggs add me on yo — Heather Schmelzlen (@anchorlines) June 18, 2014

-- Keith Wagstaff