Doing a search is your best bet for general queries.

General idea:

You know how you can enclose something inside braces and it is only visible inside the braces? Like:


That's called a variable's 'scope'
Well, namespaces allow you to NAME a scope, like this:
Think of them as 'named globals', almost as if they belonged to a struct. But a namespace is not a description of things (like a struct would be), it is an implementation of things. That is, the Chainsaw::i was declared as a variable inside the namespace just as if it were a global variable.

I`ll try.
std is a namespace, and std::cout, refers to the object in std called cout.
So you can define an object called cout, without breaking the one definition rule. For example: In a large program, many programmers work together, and the possebility for several programmer have defined object with the same name, is huge. So if every programmer(or a programmer group) have defines a namespace, it doesn`t matter if several programmers have define the same name on several object`s as long as it`s in a namespace.

Edit: oops, I didn`t see the other threads.