A magical girl anime about a normal elementary schoolgirl named Takamachi Nanoha who discovers a magical devise called Raising Heart and becomes a complete beamspamming badass.
It begins as a rather clinched Magical Girl anime until the introduction of Nanoha's rival/possible love interest, Fate Testarossa.
Nanoha threw out many Magical Girl conventions, using more shounen-style elements than shoujo, such as power battles and fast-paced storytelling. There are two sequels, A's being the better received compared to StrikerS.
Anonymous B: Yeah, A's was definitely the best of the series. If only they did without the Final Fantasy Final Boss at the end.