Why does Bitcoin proof-of-work use SHA256

Tanya Matveeva asked me, "Why does Bitcoin use SHA256? Is it the best - the easiest?"

From a programmer's perspective, all cryptographic hash functions are about equally easy to use, as they are provided in software libraries (don't roll your own, kids!).

In this video, I look at both the technical and the historic reasons why SHA256 is used.

[filippetr.]

Assuming NSA built Sha, is there any valid proof that function itself doesnt hold some deep mathematical backdoor and is there a solid proof that it isnt two way in sense that someone can by using some mathematical concept and by abusing structure of sha reverse hash - > input. Fun fact is that Russian government and some Eastern governments countries forbid usage of Sha on these diplomatic levels where hashing is needed

[Test-buzr]

Few days back you spoke about a blockchain solution for open source programmers gain some money for their code contribution to open-source projects. Can you make a video about it?