In the US methods of doing things can be patented. That includes software. Look up MP3, LZW compression, or perhaps IBM's 2100 algorithm patents over the fifteen years from 2001 to 2016.

It's being narrowed, but it still exists. Until rather recently many courts would recognize "do well understood process X, but on a computer" as patentable.

http://blogs.gartner.com/doug-laney/patents-for-algorithms-h...

https://news.ycombinator.com/item?id=8310084

http://www.legalmatch.com/law-library/article/what-cant-be-p...

Maybe it's just me, but as far as my experience goes, the App store and Google Play, and to a much lesser extent Steam have done much, much more killing my ability to make a profit on software than patents ever have.

Maybe it ought to be this way, but it's clearly not. MP3, GIF, patent trolls, and the Eastern District of Texas are all well-known examples of software patents.