The word application has several meanings:

1. A formal request for something, like a job, a school, or a program. When you fill out an application for summer camp, you're asking to be accepted and providing information about yourself. College applications ask students to share their grades, interests, and goals. The verb form is apply: you apply to a school or apply for a job.
2. A computer program designed for a specific purpose. The games on your tablet, the word processor you use for homework, and the map program in your family's car are all applications, often shortened to apps. Each application does particular tasks: a drawing app lets you create art, while a calculator app does math.
3. The act of putting something to use. When you learn about fractions in math class, you might not see the application at first, but when you're halving a recipe or splitting pizza with friends, you're seeing those fractions in action. A science lesson on air pressure has practical applications when you're inflating a bicycle tire. The verb is apply: you apply what you learned in class to real situations.