Muggles' Guide to Harry Potter/Magic/Reparo

Overview
Reparo is a spell for fixing broken things, for example a glass bowl that has broken into several pieces. It can also be used to counter the effects of the Diffindo charm.

Extended Description
This spell was first used by Arthur Weasley on Harry's glasses in Harry Potter and the Chamber of Secrets, shortly after Harry's exit from Knockturn Alley, though the incantation is not heard there. Curiously, it is also the last spell we see actually cast in the series.

This spell is used a number of times through the series to repair things – dropped glass or china bowls, broken windows, torn bags, or torn books, for instance.

Analysis
It is only in the final book of the series that we learn that it can be used to repair magical items, when Hermione tries to mend Harry's wand with it, and later when Harry successfully mends his own wand. Until that point, only non-magical items had been repaired with this charm.

This spell seems to be useful only for inanimate objects – it is not used on Harry's broken wrist, for example. (Though the charm that is used on his wrist in Harry Potter and the Chamber of Secrets does not have the desired effect...)