Back-End Development — Servers, Databases and APIs

Back-end development is everything that happens on the server: handling requests, storing data, checking who someone is, and deciding what they are allowed to see.

The front end asks. The back end answers, and decides whether the question was allowed.

What the job actually involves#

• Building APIs the front end can call
• Storing and retrieving data from a database
• Authentication (who are you?) and authorisation (what may you do?)
• Validating anything that arrives from outside — never trust the client
• Handling failure sensibly when something downstream breaks

The concepts, in order#

1. A language. Python or JavaScript with Node are the common starting points. Whichever you already know is the right one.
2. How HTTP works. Requests, responses, methods (GET, POST, PUT, DELETE), status codes, headers. Learn this properly — it explains a lot of confusing behaviour later.
3. A web framework. Flask or FastAPI for Python; Express for Node. Start with the smallest one.
4. Databases and SQL. Tables, relationships, and how to ask questions of them. SQLite is perfect for learning — it is a single file.
5. Building a REST API. Predictable URLs, sensible status codes, JSON in and out.
6. Authentication. Password hashing (never store plain passwords), sessions or tokens.
7. Deployment. Getting it running somewhere other than your laptop.

Security basics you must know#

These are not advanced topics. They are the baseline.

• Never build SQL by joining strings. Use parameters, or you have an injection vulnerability.
• Never store passwords as plain text. Use a purpose-built hashing function.
• Never trust anything from the client. Validate on the server, always. Front-end checks are for convenience, not safety.
• Keep secrets out of your code. Environment variables, and a .gitignore entry for .env — see Git and GitHub explained.

A realistic first back-end project#

Take the to-do list that saves to a file and turn it into an API:

1. Replace the file with a SQLite database
2. Add endpoints: list tasks, add a task, mark done, delete
3. Return JSON with correct status codes
4. Connect a browser front end to it with fetch

Doing that once teaches you more than a dozen tutorials, because you meet every real problem: shapes of data, error handling, and the CORS rule.

What to skip early#

Microservices, Kubernetes, message queues, GraphQL and caching layers all solve scaling problems. Build the simple version first; you will understand the complicated version far better for having needed it.

NextHow the front and back ends meet