The CRC32 algorithm is a member of the CRC family, namely the 32-bit version. 32-bit refers to the length of the checksum returned by the function. While less secure than, for instance, an MD5 checksum, the CRC32 algorithm is still very fast and good in that is highly numerically unstable. Originally, it was implemented in a serial fashion using simple register shift operations, but modern implementations tend to be parallell and thus approximately ten times faster.
The CRC32 algorithm is used in the zip compression system, and during the mid-nineties it was ubiquitous in z-modem implementations. For a good while this was the only places where you would see it as a non-programmer, but the last few years have seen it being used in the many SFV, or Simple File Validator, programs used in the piracy scene.
It should be noted that the different variations of CRC32 are not necessarily compatible, e.g. java.util.zip.CRC32 is not compatible with SFV or the freeware Java implementation floating around the net.