How many bits are in a kilobyte?

This is actually one of the most commonly misunderstood terms.

First off, there are 1000 bytes (B) in a kilobyte (kB). kilobytes, megabytes, etc. are measured in base 10.

Then, there are 8 bits in a byte. So altogether, there are 8000 bits or 8 kilobits (kbit) in a kilobyte.

The base 2 notation is known as a kilobinary byte or kibibyte (KiB) and is equal to 1024 bytes. The numbers are close but the terms are often misused.

There is an article from NIST on the correct notations attached to this answer.