Facebook has Instagram. Google has YouTube. And soon, Yahoo will have Tumblr. The Internet giant's board unanimously approved a $1.1 billion cash deal to buy the blogging site Sunday. It's a risk for Yahoo, since Tumblr doesn’t really make that much money, though it has been valued at $800 million. The move highlights a growing trend of monster tech companies buying startups to get an edge in the market. Now Yahoo, once considered a prehistoric company, has a thriving social network. Marissa Mayer announced on her own Tumblr page that Tumblr would continue to operate independently and “we promise not to screw it up.” Tumblr founder David Karp also issued a statement on Tumblr, promising its mission to “empower creators to make their best work and get in front of the audience they deserve” isn’t changing.