You probably don't spent a whole lot of time in your Start menu but some of the boxes in there are promoted apps which Microsoft serves to you in an attempt to get a few more downloads from the store.
These promoted apps appear as tiles in your menu and look pretty much like content that is installed on your computer. They aren't though, with a click taking you to the store to download the program.
With the upcoming Anniversary update, the number of promoted app would increase from 5 to 10, according to Neowin. This will also see the number of 'static apps' (preinstalled content) reduce from 17 to 12.
Basically Microsoft will be putting a fair amount of apps in your Start menu that it wants you to look at because they are being paid, and it will also continue to install stuff that you don't really want.
The good news is that you can unpin any tile you're interested in and easily uninstall any content which is unwanted, so at least there's that.
The Windows 10 Anniversary update is coming in Summer, 2016.