Apogee and Ejection
The definition of Apogee is the highest point of something. In the case of rocketry, the Apogee is the peak of flight, its highest point traveled. Several things happen at the Apogee. First off, the Velocity of the rocket is equal to zero. The rocket is literally no longer moving in the y-direction. Second, it is the location where the velocity switches direction. Preceding the apogee, the rocket's velocity is positive. Post-apogee, the rocket's velocity is negative.
For Rocketry, the Apogee is usually the desired location for parachute deployment. There are several different types of parachute deployments. Single Deployment, double deployment and side deployment.
Single deployment consists of one parachute, deploying from the interior of rocket, through the top of the rocket. For beginners and amateurs, this is the usual deployment technique.
Dual and Side deployment are more advanced parachute deployment techniques. Dual Deployment consists of the deployment of an initial, small parachute, called a drogue. This second parachute applies a tension force on the rocket, triggering the second main parachute. Side deployment is just the deployment of the parachute from the side of the rocket.