TDWG Terms Wiki supports the OpenID standard for single sign-on between websites. OpenID lets you log in to many different websites without using a different password for each. (See Wikipedia's OpenID article for more information.) There are many OpenID providers, and you may already have an OpenID-enabled account on another service.
If you already have an account on TDWG Terms Wiki, you can log in with your username and password as usual. To use OpenID in the future, you can convert your account to OpenID after you have logged in normally.