The 'ge-' prefix in German marks a past participle. For example: sagen = to say (ich sage - I say/am saying) gesagt = said (ich hage gesagt - I have said) Some verbs with particular prefixes (such as be-, er-) don't take this prefix when forming the past participle.

Hello, Adam is right that the prefix ge- forms the past tense in German, but "gebrauchen" is also a verb itself. gebrauchen = brauchen, verwenden, benutzen > to use: Peter gebraucht / benutzt den Hammer, um einen Nagel in die Wand zu schlagen. http://www.duden.de/rechtschreibung/gebrauchen