[bmitc]

It's actually pretty easy if you're new to .NET. If that's the case, it's just .NET 8 and forget about everything else.

.NET Core was renamed to .NET 5, which became the mainline .NET. .NET 8 is simply the latest version.

.NET Standard is intended to be a common layer to help bridge between .NET Framework and .NET Core and .NET 5+. It shouldn't be used outside of that context.

.NET Framework is the old, Windows-only .NET. It should not be used for new projects and should be migrated away from.

[sebazzz]

Think of ".NET Standard" as "the common .NET Standard on which you can build cross-framework libraries".

[bmitc]

It is my understanding that it isn't recommend though anymore. In that it should only be used if you really want your library used in .NET Framework. My vague recollection is that it keeps you away from some of the benefits of the modern .NET.