A parity bit is a binary digit (bit) that is added to data to make the number of 1’s either even (in even parity) or odd (in odd parity). It’s a simple error detection scheme to check the integrity of data.

**How It Works**:

**Even Parity**:

- If the number of 1’s in a given set of data is odd, the parity bit is set to 1.
- If the number of 1’s is even, the parity bit is set to 0.
- This ensures that the total number of 1’s, including the parity bit, is always even.

**Odd Parity**:

- If the number of 1’s in a given set of data is even, the parity bit is set to 1.
- If the number of 1’s is odd, the parity bit is set to 0.
- This ensures that the total number of 1’s, including the parity bit, is always odd.

**Usage**:

- When data is transmitted or stored, a parity bit is added based on the original data.
- When the data is read or received, the parity is checked. If it doesn’t match the expected even or odd parity, an error is detected.

**Example**:

Let’s consider a byte of data: **11010101**.

- For
**even parity**, since there are 5 ones in the data, the parity bit would be set to 1 to make the number of ones even (total 6 ones). The transmitted byte would be:**110101011**. - For
**odd parity**, the parity bit would be set to 0 (because there are already an odd number of ones). The transmitted byte would be:**110101010**.

**Advantages**:

**Simple to Implement**: Requires minimal hardware or software overhead.**Quick Detection**: Can quickly detect single-bit errors.

**Limitations**:

**Limited Error Detection**: Can only detect an odd number of bit errors. It cannot detect errors when an even number of bits have changed (since the parity would still appear correct).**No Error Correction**: While it can detect some errors, it doesn’t indicate where the error is or provide a means to correct it.

In practical applications, parity is often used in combination with other error detection and correction techniques, especially where higher reliability is required.