Check Engine light question

i have a 1998 mazda protege with 76,000 miles on the engine. I was driving down the road about an hour ago and the check engine light came on. Does this mean something is wrong with the engine? what should be my next move? (I know little about cars)

definitly, take it to the dealer/personal mechanic
it could be from anything simple as air in the gas tank
to pistions not firing correctly(major engine problem)
but, judging from the car, '98 and only 76K
it is just something that wore down and needs replacement

quick answer, YES, take it ASAP and get it checked