Server Logic: Write code that processes user requests, runs business rules, and performs calculations behind the scenes.
Database Management: Design, store, organize, and retrieve data safely using relational (like PostgreSQL, MySQL) or non-relational (like MongoDB) databases.
APIs (Application Programming Interfaces): Build bridges so the frontend (what users see) can talk to the backend (where data lives).
Security & Authentication: Handle user logins, permissions, data encryption, and protection against attacks.
Performance & Scalability: Optimize server speed and make sure the system can handle thousands or millions of concurrent users.