I watched Ben Eater’s videos How do CRCs work? and Checksums and Hamming distance (the full course is Learn about error detection) then found the Wikipedia page: Cyclic redundancy check.

Also of interest:

• Best CRC Polynomials by Philip Koopman, Carnegie Mellon University
• Cyclic code
• Error correction code
• Systematic code
• Polynomial code
• Polynomial long division
• GF(2)
• Mathematics of cyclic redundancy checks
• Computation of cyclic redundancy checks