Software engineers design, develop, test, and maintain software applications. They analyze user needs to determine requirements, design and code software solutions, conduct testing, and release updates. Common roles include front-end engineers who work on user interfaces, back-end engineers who focus on server-side code, full-stack engineers who work across front-end and back-end, QA engineers who test software, DevOps engineers who manage infrastructure, and security engineers who ensure software safety. A typical day involves researching solutions, writing code, collaborating with others, and releasing updates.