Thank you for supporting the Physical World Database Project.

The basic service is free.

The Physical World Database project is financially supported in three ways.

1. Credits are sold for 38 cents each that allow an author to lock a database file so that only the author can edit it. This lock is good for one year and manually renewed if desired.
2. Advertisements may be served with database files that are not locked.
3. Corporate sponsorship and a standards advisory board.