- A checksum is a form of error detection code
- It is usually an affix to a piece of data, created through running an algorithm on the data
- It is a form of redundancy
- Information redundancy: If packet is valid, the checksum is unnecessary
- Partial Redundancy: If packet is invalid, the packet cannot be reconstructed from the checksum
- If the checksum is "strong enough" ( i.e. has a high minimum hamming distance ) it is possible to reconstruct a "most likely" correct packet
- In this case the partial redundancy is removed