📚 50+ Terms
Stuck on a word while learning to code? Look it up here. Plain English. Real examples. No textbook speak.
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How to use this glossary: When you hit a word you don’t recognize while reading — search it here. Read the definition, check the example, and move on. You’ll remember it naturally as you practice. No cramming needed.
😕 No terms found for ““. Try a different word.
Core Terms
Fundamental building blocksVariable Core
Picture a sticky note on your wall. You write something on it, slap a label on top, and whenever you need that info — you just read the label. That sticky note is a variable. It holds one value at a time.
city = “California”
Array Core
Instead of 10 sticky notes scattered everywhere, imagine one notebook with numbered pages. Each page holds one value. That notebook is an array — one variable, many values, all in order.
students = [“Ali”, “Sara”, “Jack”]
Loop Core
You know how a washing machine spins the same cycle over and over until it’s done? A loop does exactly that — runs the same block of code again and again so you don’t have to write it out each time.
for i in range(5): print(i)
Function Core
Think of a function like a recipe. You write the steps once, give it a name like “makeChai”, and then any time you want chai — you just call that name. No rewriting. Just call it.
def make_chai(): print(“Brewing!”)
String Core
Any text in programming lives inside quotes — that’s a string. Your name, a message, a city, an emoji — if it’s wrapped in quotes, it’s a string. The computer treats it as text, not a command.
“Salam!” | “basiccodingconcepts.net”
Object Core
Imagine a contact card in your phone — it has a name, number, city, all for one person. An object works like that. One variable that holds multiple pieces of related information together.
person = {name:”Jack”, age:22}
Index Core
The address of an item inside an array. But here’s the catch — computers start counting from 0, not 1. So the first item lives at index 0. The second at index 1. Always one less than you’d expect.
students[0] → “Ali” (first item)
Comment Core
A note you leave inside your code — for yourself or anyone else reading it later. The computer skips it completely. It’s like writing a sticky note on the side of a textbook — the book doesn’t care, but you do.
# This prints the user’s name
Data
Types of informationData Type Data
Every value in your code belongs to a category. The number 5 is different from the text “5”. One you can do math with. One you can’t. Data types tell your program which category a value falls into.
5 is int | “5” is string
Integer (int) Data
A whole number — nothing after the decimal point. Great for counting things that can’t be half — students in a class, items in a cart, years of experience.
age = 22 | score = 95
Float Data
A number that has a decimal point. Use it when precision matters — prices, percentages, GPS coordinates. Anything that can be “between” two whole numbers.
price = 499.99 | score = 8.5
Boolean Data
The simplest data type possible — it’s either True or False. Nothing else. Used to answer yes/no questions in your code. Is the user logged in? Is the score above 50? Yes or no.
is_online = True | passed = False
None / Null Data
The value that means “nothing is here yet.” Like an empty field on a form — it exists, but nothing has been filled in. In Python it’s None. In JavaScript it’s null.
result = None ← no value yet
Dictionary Data
Like an actual dictionary — you look up a word to find its meaning. In Python, you look up a key to find its value. Perfect for storing things that naturally come in pairs.
{“city”: “California”, “country”: “USA”}
Operator Data
The symbols that do the work in your code. Math operators add and subtract. Comparison operators check if things are equal or greater. Logic operators combine True/False conditions.
+ – * / == != > < and or
Concatenation Data
Joining two strings together into one. Like gluing two pieces of paper side by side. “Hello” + ” ” + “Ali” becomes “Hello Ali”. Simple idea, fancy name.
“Hello” + ” Ali” → “Hello Ali”
Control Flow
How programs make decisionsIf / Else Control Flow
Your program’s decision maker. “If it’s raining, take an umbrella. Otherwise, wear sunglasses.” Without if/else, your code does the same thing every time — no matter what.
if marks >= 50: print(“Pass”)
For Loop Control Flow
Best for when you know exactly how many times to repeat. “Do this 10 times.” Or “go through every item in this list, one by one.” Clean, predictable, reliable.
for name in names: print(name)
While Loop Control Flow
Best for when you don’t know the count in advance. “Keep asking for a password until the user gets it right.” It runs as long as the condition stays true — then stops on its own.
while not correct: ask_again()
Break Control Flow
An emergency exit for loops. The moment your code hits break, it leaves the loop immediately — no matter how many rounds are left. Useful when you’ve found what you needed.
if found: break ← exit now
Continue Control Flow
Not an exit — just a skip. “Skip this round, keep going.” The loop stays running, but the current item is ignored and execution jumps straight to the next one.
if x == 0: continue ← skip zero
Condition Control Flow
A question your code asks — and the answer is always True or False. “Is the user logged in?” “Is the score above 80?” The result of that question controls what happens next.
age >= 18 → True or False
Iteration Control Flow
One complete run of a loop. If your loop runs 5 times, it has 5 iterations. You’ll hear developers say “on each iteration” — they just mean “each time the loop goes around.”
5 loops = 5 iterations
Nested Loop Control Flow
A loop inside another loop. Like a clock — the minute hand completes a full circle for every single tick of the hour hand. Useful for working with grids or tables.
for row in grid: for col in row:
Functions
Reusable code blocksParameter Functions
A blank field inside a function waiting to be filled. Like a form that says “Enter Name Here” — parameter is the blank. You fill it in when you actually call the function.
def greet(name): ← name is blank
Argument Functions
The actual thing you fill into that blank field. When you call greet(“Sara”), you’re passing “Sara” as the argument — it fills the name parameter inside the function.
greet(“Sara”) ← “Sara” fills blank
Return Functions
A function that just prints something is like a microwave that beeps but gives you nothing. Return actually hands the result back to you — so you can store it, use it, or pass it on.
def add(a,b): return a + b
Scope Functions
Where a variable can and can’t be seen. Variables created inside a function stay there — like what happens in a room, stays in the room. Outside code can’t see them.
x inside def → invisible outside
Arrow Function Functions
JavaScript’s shortcut for writing functions. Same result — just less typing. The ⇒ symbol replaces the word “function”. Once you see them, you’ll spot them everywhere in modern JS code.
const double = n => n * 2;
Default Parameter Functions
A safety net for your function. If someone calls it without passing a value, the default kicks in automatically. Like a cafe that gives you regular milk unless you ask for oat.
def order(drink=”tea”): …
Method Functions
A function that belongs to something. .upper() belongs to strings. .append() belongs to lists. You call a method using a dot — it knows what object it’s working on automatically.
“California”.upper() → “California”
Calling a Function Functions
Defining a function writes the recipe. Calling it actually cooks the food. You call a function by writing its name with parentheses — that’s what triggers the code inside to run.
make_chai() ← this runs it now
Errors & Debugging
Finding and fixing problemsBug Errors
Any mistake in your code that makes it misbehave — crash, give wrong output, or act strangely. Not a sign you’re bad at coding. Every developer writes bugs. The good ones just find them faster.
Wrong formula = wrong result = bug
Debugging Errors
The detective work of coding. Something’s wrong — you don’t know what or where. Debugging is the process of tracking it down and fixing it. A skill you’ll use every single day, forever.
Add console.log() → find the bug
Syntax Error Errors
You broke the grammar rules of the language. A missing bracket, a typo in a keyword, a forgotten colon. Your code won’t even start until it’s fixed — but the error message usually tells you exactly where to look.
print(“Hi” ← missing closing )
Runtime Error Errors
Code that starts fine but crashes mid-run. Syntax was perfect — the problem only showed up when the program was actually executing. Like a car that starts fine but stalls at a red light.
Accessing index 10 in a 5-item list
Logic Error Errors
The sneakiest bug. No crash. No error message. Code runs perfectly — and gives you the wrong answer. Like following a recipe correctly but using salt instead of sugar. Everything “works” but tastes terrible.
÷ 3 instead of ÷ 2 for average
console.log() Errors
JavaScript’s most used debugging tool — and honestly one of the most used tools in all of web development. Print any value to the browser console and see exactly what your variable holds at that moment.
console.log(total); → see value
Error Message Errors
The text your program shows when something breaks. Most beginners close it in a panic — that’s a mistake. Read it. It tells you the error type, the file, and the exact line number. That’s free debugging help.
NameError: ‘x’ is not defined, line 5
Exception Handling Errors
A way to deal with errors without crashing. You “try” something risky, and if it fails, the “except” block catches it and handles it gracefully — like a safety net under a tightrope walker.
try: risky() except: handle_it()
General Programming
Common terminologyAlgorithm General
A clear, step-by-step plan to solve a problem. Not code — just the logic. Like directions to a place: turn left, go straight, turn right. Code is just how you write those directions in a language a computer understands.
Sort list → compare → swap → repeat
Syntax General
The rules of how to write code in a specific language. English has grammar rules — programming languages have syntax. Break a syntax rule and your code simply won’t run. Different languages, different rules.
Python needs : and indentation
IDE General
The app where you write code. IDE stands for Integrated Development Environment — fancy way of saying “a code editor with extra tools built in.” VS Code is what most beginners (and professionals) use.
VS Code, Replit, PyCharm
Output General
Whatever your program produces and shows to the user. Text on screen, a downloaded file, a sound — anything your code sends out into the world. print() in Python, console.log() in JS.
print(“Salam!”) → Salam! on screen
Input General
Data that comes into your program from the outside world. A user types something, a file is uploaded, a button is clicked — all of that is input. Without input, programs can’t respond to the real world.
name = input(“Your name? “)
Library / Module General
Code someone else already wrote that you can borrow. Need to do math, generate random numbers, or work with dates? There’s already a library for that. No need to build everything from zero.
import random | import math
API General
A way for two programs to talk to each other. Think of a waiter — you don’t go into the kitchen yourself, you tell the waiter what you want, and they bring it back. The waiter is the API.
Weather app asks weather API for data
Open Source General
Software whose source code is open for anyone to read, use, or improve. Most of the tools you’ll use as a beginner — Python, VS Code, React — are open source. Free because thousands of developers built them together.
Python, VS Code, Linux are open source
Version Control General
A system that saves every version of your code as you build it. Made a mistake that broke everything? Roll back to yesterday’s version. Git is the tool. GitHub is where developers store and share those versions.
git commit -m “added login page”
Compiler / Interpreter General
Your code is human-readable — computers need machine instructions. A compiler translates everything at once before running. An interpreter does it line by line as it runs. Python interprets. C compiles.
Python → interpreter → runs line by line