1. Local Variables

These are declared inside a function or a block (between { }).

• Scope: Only accessible within the function where they are defined.

• Lifetime: They are created when the function starts and destroyed when it finishes.

• Default Value: Contains "garbage" (random data) unless initialized.

2. Global Variables

These are declared outside of all functions, usually at the top of the program.

• Scope: Accessible by any function throughout the entire program.

• Lifetime: They exist for the entire duration of the program.

• Default Value: Automatically initialized to 0.

3. Static Variables

Static variables are declared using the static keyword. They have a unique behavior:

• Scope: If local, they stay within the function; if global, they stay within that specific file.

• Lifetime: They retain their value between function calls. They are initialized only once.

4. External (extern) Variables

Used when you want to share a variable across multiple files. The extern keyword tells the compiler that the variable is defined in another file.

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