Sprites are bitmap images used to represent characters, props, and backgrounds in a game. The name of each sprite is important for referencing it in code. Sprites can be resized but larger sprites use more memory. Objects represent anything that moves or is animated in the game through events and code. Levels provide a space to test player controls and movement limits can be set through coding restrictions on coordinates. Parallax scrolling allows multiple background layers to move at different speeds to create depth. Particle effects can make objects like barrels appear more realistic by emitting smoke. Enemies can be given animated sprites and spawn from enemy spawner objects while being destroyed by collision with player projectiles.