Basic sharing means that users can share termbases with users that are in their SDL account but not externally with any other users. For sharing within the account, users can login using the same SDL account. You can find out which account you are using (and the other people on the same account) by visiting your SDL account at
https://oos.sdl.com/asp/products/ssl/account/accountdetails.asp. Any users logging in using the same SDL account will see each other's termbases and will be able to access them.
When using the Personal Language Cloud Terminology package, basic sharing is limited to up three concurrent users. As an example of concurrent accesses, a termbase open in your browser and a termbase accessed from Studio at the same time counts for two concurrent sessions. For sharing with more users and also for sharing with users outside of your account, consider purchasing the Business package which offers advanced sharing. For more information, see the KB article on advanced sharing.