1 day is not 24 h

[Erdem]

according to these theories; I belive every following day a day is becomming shorter. but we dont feel it.

[jcsd]

There are actually 4 simulataneous 24-hour days:

http://www.timecube.com/

On a serious note, the days are getting longer as the Earth 'slows down', If I remember correctly during the jurassic period one day was only 23 hours long.

[Nereid]

This may be a more unemotional description of 'day', including several uses and how it changes over time:
http://scienceworld.wolfram.com/astronomy/Day.html