Confusion with Tapering

I have talked to people and they say things like "yeah but once im tapered ill lose another 4 seconds or such" I searched through the forums and didnt see much explaining what tapering is except that it is a rested period before a meet. Last year i consistently swam 1 12s (100 scy ***) and then i tapered for almost my last two weeks to get my best time before the last meet of the season. But i ended up gaining a second in that meet and swam a 1 13... so what kind of sets are you supposed to do while tapering? when we tapered as a team we swam short yards on long intervals... like 50s on the 2 minutes. I was tlaking to a couple kids today about their tapering and they said they do hard sets but a lot of rest between sets to build your pace up.. like 100s on the 1 15 but after the set, rest for like 10 minutes and then the day before the meet you do like one small hard set and then rest. The kid i was talkign to ended up dropping like 4-5 seconds off a 100 after tapering... So really my question is what kind of sets are you supposed to do for tapering? and is tapering SUPPOSED to quicken your time? cause to me it seems i swim the best the day after i have a really long hard practice