What does it mean to say that a framework “scales well”?

Question

When reading about frameworks (.net. ruby on rails, django, spring, etc.), I keep seeing so and so does or doesn\'t scale well.

What does it mean when someone says that

Answer 1

Scaling means how easy it is to satisfy more demand by using more hardware.

Example: You have a website written in some language that gets 1000 visits a day. You get featured in some prominent magazin and your number of users grows. Suddenly you have 1000000 visits a day, thats 1000 times as much. If you can just use 1000 more servers to satisfy the grown need of resources, your website scales well. If on the other hand you add 2000 servers but still users can't connect, because your database can only handle 1000 requests per day, than your website does not scale well.