Containers are lightweight, portable units that package software applications and their dependencies together. They allow developers to create, test, and deploy applications consistently across different environments. By using containers, applications can run smoothly on any system that supports them, making it easier to manage and scale software. One popular tool for managing containers is Docker, which simplifies the process of creating and running these units. Containers are often used in cloud computing, where they help optimize resources and improve efficiency. This technology has transformed how developers build and deliver applications, enabling faster updates and better collaboration.