I couldn't find it anywhere on the docs or in a few google searches. What is a porter? and how does it differ from a developer? I understand the general concep

I couldn't find it anywhere on the docs or in a few google searches. What is a porter? and how does it differ from a developer? I understand the general concept of porting (ie https://en.wikipedia.org/wiki/Porting https://en.wikipedia.org/wiki/Porting) but never heard of it as a specialization. Also what might people be porting from? If this intended as a migration guide.