Database

You know how your phone has a contacts app? Each contact has a name, phone number, email, maybe an address. Now imagine that same idea, but for a million contacts, and instead of contacts it could be anything — user accounts, recipes, orders, messages, product listings.

That's a database. It's a structured way to store, organize, and retrieve data. When you sign up for a website, your account info goes into a database. When you post on social media, your post goes into a database. When you search for a product on Amazon, it's searching a database.

There are two main flavors: SQL databases (like PostgreSQL or MySQL) that organize data in tables with rows and columns — think spreadsheets on steroids. And NoSQL databases (like MongoDB) that are more flexible about structure — think organized piles instead of strict tables.

Because every app that remembers anything uses a database. If you build something that needs to save user data, store content, or keep track of anything — you need a database. The good news: services like Supabase and Firebase make this way easier than it used to be. You don't need to manage servers — they do it for you.

Databases come in several types: relational (PostgreSQL, MySQL — ACID compliant, SQL queries), document (MongoDB — flexible schemas, JSON documents), key-value (Redis — blazing fast, in-memory), and vector (Pinecone, pgvector — for AI embeddings). ORMs like Prisma and Drizzle abstract SQL into application code. Connection pooling, indexing, and query optimization are key performance considerations.