4. Core Concepts Every Developer Must Know

📦 Variables — Storing Information

A variable is a named box that holds a value. You give it a name, put something in it, and refer to it by name later.

Variables can hold different data types:

🔀 Conditionals — Making Decisions

Code needs to make decisions based on data. if/else statements are how computers choose what to do:

Every condition evaluates to either True or False. If the condition is True, that block runs. Otherwise, the next condition is checked.

🔁 Loops — Repeating Actions

Loops let you repeat a block of code without writing it out hundreds of times:

🧰 Functions — Reusable Blocks of Code

A function is a named, reusable block of code. Instead of writing the same logic ten times, you write it once as a function and call it whenever you need it:

Functions take inputs (called parameters), do something with them, and return an output. Every piece of code in every application is built from functions calling other functions.

📚 Libraries — Standing on the Shoulders of Giants

A library is a collection of pre-written code that you can import and use for free. Instead of writing your own code to handle images, send emails, or connect to a database — someone already solved that problem and published a library.

🗄️ How Data is Stored

Every application needs to store data — user accounts, posts, orders, messages. Data lives in different places depending on how it's used: