In Python, [`if`][if statement], `elif` (_a contraction of 'else and if'_) and `else` statements are used to [control the flow][control flow tools] of execution and make decisions in a program.
Unlike many other programming languages, Python versions 3.9 and below do not offer a formal case-switch statement, instead using multiple `elif` statements to serve a similar purpose.
Python 3.10 introduces a variant case-switch statement called `pattern matching`, which will be covered separately in another concept.
Conditional statements use expressions that must resolve to `True` or `False` -- either by returning a `bool` directly, or by evaluating ["truthy" or "falsy"][truth value testing].
```python
x = 10
y = 5
# The comparison '>' returns the bool 'True',
# so the statement is printed.
if x > y:
print("x is greater than y")
...
>>> x is greater than y
```
When paired with `if`, an optional `else` code block will execute when the original `if` condition evaluates to `False`:
```python
x = 5
y = 10
# The comparison '>' here returns the bool False,
# so the 'else' block is executed instead of the 'if' block.
if x > y:
print("x is greater than y")
else:
print("y is greater than x")
...
>>> y is greater than x
```
`elif` allows for multiple evaluations/branches.
```python
x = 5
y = 10
z = 20
# The elif statement allows for the checking of more conditions.
