Chapter 1 What is Database (Real World Understanding)

A database is basically a system that helps apps remember things. Think about your phone. Your contacts, chats, bank history, and social media data are still there even after you restart your phone. That is possible because this data is stored in databases, not in temporary memory like RAM, which forgets everything when power is off.

You can imagine a database like an Excel sheet, but much more powerful. It can store huge amounts of data, find information very fast, keep it secure, and allow many users to use the same data at the same time. This is why all real-world apps depend on databases.

Databases mainly work using four simple actions. They add new data, show existing data, update old data, and delete unwanted data. Almost every app you use daily works on these basic actions in the background.

Some people think text files can store app data, but they are slow, unsafe, and not reliable for large or multi-user apps. If you want to build real applications or become a backend developer, learning databases is very important. PostgreSQL is one of the most trusted databases used by many companies today.