Skyr Is Not Yoghurt
Every skyr sold outside Iceland is labelled as a yoghurt, or as "yoghurt-style," or as "high-protein yoghurt alternative." All of these are marketing decisions rather than accurate ones.
Skyr is a fresh cheese. The distinction isn't pedantry — it explains why it tastes the way it does, and why the versions made elsewhere usually don't.
The rennet is the whole argument
Yoghurt is milk acidified by bacterial culture. That's it. Skyr is milk that has been both cultured and set with rennet, the same enzyme used to make cheddar, feta, or halloumi. The rennet forms a curd. The curd is then strained.
Strained hard. Roughly four litres of skimmed milk produce one of skyr, which is why the protein content is where it is and why the texture is closer to something you could stand a spoon in than something you pour.
By any working definition used in a dairy, that is a cheese.
The whey has a name and a second life
The liquid that drains off is called mysa — sour whey. Elsewhere it goes down the drain. In Iceland it was a preservative: meat and blood sausage were stored in it through the winter, which is where the sour edge in traditional súrmatur comes from.
People still drink it. It's an acquired taste in the specific sense that most Icelanders acquired it as children and most other people never will.
A thousand years, more or less unchanged
Skyr appears in the medieval Icelandic sagas, which puts it in the country from close to the settlement period. That's a long continuity, and it survives partly because Iceland was too poor and too isolated for the process to be industrialised away. Skimmed milk was what was left after the cream went to butter. Nothing was wasted.
This is where we'd normally tell you the tradition makes it taste better. It doesn't, particularly. What it means is that the sourness and the density are the point rather than a defect, and that low-fat imitations made without rennet are solving a different problem.
Skyr against Greek yoghurt
Greek yoghurt is strained yoghurt: cultured, no rennet, usually higher fat. It's rounder, milder, creamier. Skyr is sharper, drier, and cleaner on the finish.
Neither is better. But if you had skyr in Iceland and came home to find that the Greek yoghurt in your supermarket doesn't taste like it, this is why. You are not misremembering.
How Icelanders actually eat it
Not with granola arranged on top for a photograph. A bowl, a little milk poured in to loosen it, sugar or berries if you want them. Often for breakfast, often standing up. Some people eat it with rúgbrauð and butter alongside, which sounds odd and isn't.
The unsweetened version is the one to buy first. If you find it too sharp, the flavoured versions are made for exactly that reaction — but taste the plain one before you decide.
Order skyr — Mjólkursamsalan, shipped from Iceland, worldwide.