HTML

Simple HTML Page 
<!DOCTYPE html>
<html>
<head><title>Hello</title></head>
<body>Hello World!</body>
</html>
HTML Table 
<table>
  <tr><th>Name</th><th>Age</th></tr>
  <tr><td>Alice</td><td>25</td></tr>
</table>

CSS

Center Content 
.center {
  display: flex;
  justify-content: center;
  align-items: center;
}
Button Styles 
.btn {
  padding: 10px 20px;
  background: #3498db;
  color: white;
  border-radius: 4px;
}

JavaScript

Hello World 
console.log("Hello, World!");
Random Number 
function getRandom() {
  return Math.floor(Math.random() * 100);
}
Event Listener 
document.getElementById("btn")
  .addEventListener("click", () => alert("Clicked!"));

Python

Hello World 
print("Hello, World!")
Factorial Function 
def factorial(n):
    return 1 if n == 0 else n * factorial(n-1)
List Comprehension 
squares = [x**2 for x in range(10)]

Other

JSON Example 
{
  "name": "Frank",
  "age": 36,
  "isStudent": false
}
Bash Script 
#!/bin/bash
echo "Hello from bash!"