What Is the Purpose of the Checksum Added to a Bitcoin Address?

A checksum is a short, fixed-length code derived from the address data and appended to it. Its purpose is to detect errors in transcription or transmission.

If a user manually types or copies the address incorrectly, the checksum verification will fail, preventing funds from being sent to a non-existent or unintended address. This is a crucial usability and safety feature, not a cryptographic security feature against preimage attacks.