Hey guys, I'm new to Advertising industry stocks. It's good to...

Hey guys, I'm new to Advertising industry stocks. It's good to see WPP is in the bottom of its sp. I'm reading its Annual report and I can see the company is working on reducing cost, merging offices, selling business, which are all good signs.
One thing I don't understand and concern is why they have so many brands? Did they do a lot of acquisition? is it a common thing for this industry?
Thanks guys.