Time is the passing of events. Time is, as TSC said, the decay of matter. Time must exist for change to happen, as without time, there would not be change, movement, or anything really. If you want to have an example of something without time, then you may be familiar with Absolute Zero, or Zero Kelvin, about -273 Degrees Celsius. At this temperature things (as in particles, even as small as electrons) stop moving. Also when you are at Absolute Zero, you are able to store information. Light itself, if shined through it, is slowed so much that it almost stops (or completely, I am not sure about that). Now, if at Absolute Zero, time almost doesn't exist, then the opposite must be true for when it is NOT absolute zero, and things can be moving. Time DOES exist in this case. Still don't believe me? Time for more physics! Sit down children!
Based on the theories of many Physicists, it was deduced that if you are traveling at or near the speed of light (since it is actually impossible to travel at the speed of light in any technology we have today), then time actually goes faster for you. This would mean that you are aging faster, showing decay of matter (or at least the change), again, showing that time must have passed. Furthermore, this means that if you step out of your vehicle that was going at that high speed, you would be in a time period that would be slightly farther into the future than the people you left behind. Meaning, their clocks were going slower to put it simply. Time can be bent like that.
Time is no physical thing that is tangible. Instead, it is the name given to passing periods of change in matter and space. What we call time exists. You cannot argue that and if you do try, then please bring in not just philosophy, but actual physics.
