[c#] C# List<string> to string with delimiter

Is there a function in C# to quickly convert some collection to string and separate values with delimiter?

For example:

List<string> names --> string names_together = "John, Anna, Monica"

You can also do this with linq if you'd like

var names = new List<string>() { "John", "Anna", "Monica" };
var joinedNames = names.Aggregate((a, b) => a + ", " + b);

Although I prefer the non-linq syntax in Quartermeister's answer and I think Aggregate might perform slower (probably more string concatenation operations).