Who's Who directories are business directories that list contact information for executives in various fields. While some Who's Who directories are legitimate publications, others are essentially scams that charge inductees exorbitant sums to be included in the directory.
The words "Who's Who" are in the public domain and so can be attached to any business publication, which has led to the creation of many incomplete or unscrupulous directories. In general, legitimate Who's Who directories do not require individuals to pay to have their information included. Any Who's Who directory that asks for money can usually be safely written off as a scam.