[vcool07]

OK, so it is open, but not free ? Is it available for academic purposes free of cost ?

[Khoth]

You have to pay royalties to actually use it, but if you just want to read the thing, you can get it for free from the ITU. https://www.itu.int/rec/T-REC-H.264-201602-S/en

[userbinator]

As the grandparent comment says, it is free for non-commercial use.

Of course, this also only applies in countries which enforce software patents.

[gcp]

No, not at all. There's even restrictions on distributing H264/AVC video files themselves.