Scope
Explain this to a non techie friend....
The question set in this weeks sprint was to explain to a non-tech person, what is 'scope' and how it works in JavaScript. Scope is a techie term for the parts of your code that have access to a variable. Simply put, variables defined outside a function are called global variables, and variables defined within a function are local variables.
An analogy i thought of might be that of differnt TV remotes. Take a Sony remote, that remote only has access to Sony TV's, because Sony TV and remotes come from the Sony factory where they were defined, just like a local varible can only access the function where that variable was defined.
But a Universal TV remote can access every TV as it was build in the Universal remote factory for every make of TV, just like a global function's scope can access the entire script, which means that you can read and change them anywhere in your code.
In the picture above, the scope of the local variable is highlighted blue – it's the function where that var was defined. Any code inside that function can access (read and change) this variable. Any code outside it can't. It's local, so it's invisible from outside.