In C, storage class specifiers define:

• Scope (where variable is accessible)
• Lifetime (how long it exists)
• Default initialization
• Storage location

There are four storage class specifiers:

auto
register
static
extern

1️⃣ auto

Meaning

auto refers to automatic (local) variables.

In fact, all local variables are auto by default.

Example:

int main() {
    auto int x;   // same as: int x;
}

Properties

• Scope → Inside the block
• Lifetime → Until block ends
• Memory → Stack
• Default value → Garbage value

⚠️ If not initialized, contains unpredictable value.