According to TechTarget, CDs, also known as compact discs, are approximately 4.72 inches in circumference. Their depth varies a bit between different designs, but most are approximately 0.05 inches.
CDs are designed with tight tolerances to ensure compatibility between different players and readers. Since they are digital, all data they contain is stored as 0s and 1s. While this increases their storage compatibility over analog storage media, it also makes them more vulnerable to damage than vinyl albums and other media. Small errors can be detected and fixed, but using cases and cleaning CDs on occasion is important to ensure the disc's longevity.