Expressions and Statements

An expression produces a value.

2 + 3

The value is 5.

A statement is an instruction Python executes.

score = 2 + 3

This statement assigns the value 5 to the name score.

Expressions Can Be Inside Statements

This line contains an expression inside a statement:

print(2 + 3)

The expression is:

2 + 3

The statement is the whole instruction:

print(2 + 3)

Python evaluates the expression, then passes the result to print().

Assignment Statements

This statement:

loss = 0.5

does not print anything. It changes what the name loss refers to.

If you want to see the value, add a print statement:

Programs Combine Values and Actions

Later, you will read lines like:

prediction = weight * x + bias

The right side is an expression. It computes a value.

The whole line is a statement. It stores that value under the name prediction.

That pattern appears everywhere in numerical code.

Assignment Is Not a Value

Do not expect assignment to show output:

score = 10

This line is useful, but silent.

prediction = 3 * 4 + 2

Separate Computing from Doing

Expressions compute values. Statements do work. Most useful Python lines combine the two.