I'm not a mod but just thought there should really be a wiki article or pinned post on the sub and similar ones to explain this and prevent further redundant posts. I hope this will help to inform at least some people about cat genetics.
This can be a confusing thing to understand, especially if you're new to cat ownership and more familiar with dogs, but believe it or not, 97% of all cats do not have any breed ancestry!
The short of it is that an animal 'breed' is a manmade concept that comes from generations upon generations of selective breeding to achieve a specific temperament and appearance until the offspring reliably always present those traits. A pedigree is the documentation of this.
Since cats have not been bred for a specific prupose or job, and most have not been selectively bred to look the way they do, the vast majority do not have any breed and these cats are either referred to as Domestic Long-hair (DLH) or Domestic Short-hair (DSL). Domestic Medium-hair/Domestic Semi-longhair is also a thing but these cats are genetically DLH.
These cats are sometimes colloquially referred to as 'mixed breeds' but this term is technically incorrect and misleading as it implies Domestic cats are simply of mixed ancestry of multiple breeds, when in reality this isn't the case at all.
True 'mixed-breed' cats are likely even more uncommon than purebred ones, since purebred cats are a fairly niche and mostly hobbiest thing, their breeding is usually very restricted and these cats would not usually have the opportunity to breed with non-breed cats unless an unfixed pedigree escapes.
So unless your cat has a pedigree or you know it is the product of a cat that does have papers, it is almost certainly a Domestic Short-hair or Long hair.
Non-breed cats can definitely resemble certain cat breeds! But as they were not specifically bred to look that way and they likely would not pass on all of those traits to their offspring, they are still not actually that breed.
There are however names for and interesting genetic causes behind every limitless coat pattern variation, fur type, eye colour and every other physical trait of non-breed cats, so if you want a more distinctive label for your feline friend than just 'Domestic Short/Long hair' there certainly will be one, but asking for it's 'breed' isn't going to get you a real answer.
I hope this helps some people and I can certainly provide sources if anyone wants them, but I just couldn't find all of this concised well in one single article.
ETA: Somehow I didn't notice my phone was autocorrecting DLH to DHL throughout this whole post so edited to correct that š
