# Cohesion

How closely the things inside a class belong together; high cohesion is the goal.

## What is **Cohesion**?

**Cohesion** is how closely the things inside one class belong together. A highly cohesive `Invoice` class deals only with invoices, not also with sending emails and resizing images.

Level: Journeyman · [More OOP terms at this level](https://www.ask-codey.com/glossary/subjects/oop/journeyman)

Updated: September 27, 2026

Source: https://www.ask-codey.com/glossary/cohesion