The push-up is a great exercise because of it's simplicity it requires nothing more than your bodies length of room and a little effort making it the perfect exercise when traveling or gym access is limited. It is also great in activating a large amount of muscle fibers recruiting the triceps, deltoids, and pectoralis major. But one of the most common unknown fact about the Push-Up is that it also recruits core stability.
One problem though faced when performing push-ups is the ability to gauge the correct intensity and volume. But recent research published in the Journal of Strength and Conditioning Research has shown that an individual performing an exercise is using about 65% of their bodyweight. This means one can accurately set a target amount of reps based on their bodyweight.
You can incorporate push-ups into your program in any way you like, but I prefer to use them at the end of a workout as a finisher exercise making for a great final pump. I use extended sets doing several different variations of the push-up consecutively to failure.
Most importantly don't look down on push-ups they are not inferior to any other exercise just another alternative exercise one can incorporate into their exercise arsenal.