Every piece of data is a value
Every program, from a calculator to a chat app, is instructions working on data. Python sorts data into types because each type supports different operations: you can multiply two numbers, but multiplying two names makes no sense. Knowing a value's type tells you, and Python, exactly what you are allowed to do with it, and most beginner crashes are type mix-ups, so this pays off from day one.
A value is a single piece of data a program works with: the number 42, the text "hello", the answer True. Every value in Python has a type. The four types you will use constantly:
| Type | Name | Examples |
|---|---|---|
int | whole number | 42, -7, 0 |
float | decimal number | 3.5, -0.25 |
str | text (a string of characters) | "hello", "42" |
bool | truth value | True, False |
Text always sits inside quotes. That is how Python tells the text "42" apart from the number 42.
Your first two functions
print() and type() are functions: named instructions built into Python. You run a function by writing its name followed by parentheses, and the parentheses hold the value you want the instruction to work on. That placement is the actual rule of the language: Python reads print(42) as "run the instruction named print on the value 42". print() shows a value on the screen, and type() reports a value's type.
Code exercise · python
Run this program. `print()` shows a value on the screen, one line per call. Notice how `type()` reports each value's type.
Quiz
In `type(42)`, what job do the parentheses do?
Quiz
Which of these values has type str?
Code exercise · python
Your turn. Print the text `Python has 4 basic types` on one line. Then print the type of `2.5`, and then the type of `False`.