Does JOIN condition work like a loop on the joined table?

Do JOIN conditions work like a loop? (like Foreach) and if so, does it run the loop on the first table (the one after SELECT) or the second table (the one after JOIN clause) ?

Let's say you have the following query:

SELECT * FROM Customers JOIN Orders ON Customers.ID = Orders.CustomerID

What I want to know is that, does this ON clause, check the condition for every record in the second table one by one, to see which one of them meets the condition?