What are some examples of projectile motion?
An object is in projectile motion if it is moving through the "air" in at least two dimensions.
The reason we have to say "air" is because there can't be any air resistance (or force of drag). The only force then acting on the object is the force of gravity. This means that the object travels with a constant velocity in the x-direction and has a uniform acceleration in the y-direction of -9.81 m/s^2 here on planet Earth.
Here is my video which introduces Projectile Motion.
Here is an introductory Projectile Motion Problem.
And you can find lecture notes for these at http://www.flippingphysics.com/algebra.html#2d