When to encode space to plus (+) or ?

Question

Sometimes the spaces get URL encoded to the + sign, some other times to %20. What is the difference and why should this happen?

Answer 1

http://www.example.com/some/path/to/resource?param1=value1

The part before the question mark must use % encoding (so %20 for space), after the question mark you can use either %20 or + for a space. If you need an actual + after the question mark use %2B.