When you first set up your workspace, you're asked two questions about security, which manage the ways in which new users can view and edit pages. You can adjust these settings in your workspace at any time by clicking on "Settings" in the upper right hand corner, and then "Workspace Security" on the left hand side.

Who can view this workspace?

Anyone
Choose this option if you want the workspace to be available for reading by anyone on the Internet. This also means that your workspace can be found by search engines and displayed on search results. If you have this question set to "Anyone," then anyone will be able to read your content without logging in.
Only people I invite or approve
This options means that users must be invited or approved for access before they are allowed to see any content on your workspace. Your workspace will not be displayed in search engine results.
Who can edit this workspace?

Anyone with an account
Select this option if you want to allow anyone with a PBworks Account to have editing rights on your workspace page. They will be given Writer level permissions on the workspace. Please be advised that it is very easy to set up a PBworks account, so only enable this option if you want the public to be able to add and edit pages.
Because all new users of the workspace are added as Writers, there is no danger of a user being added to the workspace and deleting all the content. Only editors and administrators have the power to delete content on a workspace.
Only people I invite or approve
This option means that an Administrator of the workspace must add the user to the Users list first. New users of the workspace will have to contact an Adminstrator to edit pages, and those users will have to be logged in if they want to edit.
Request Access

By default, this feature is turned on. When users come to a private workspace, or a public workspace with limited editing, they can request access to join your workspace. Workspace admins will receive a notification asking them to approve the request.
Reader Comments

By default on new workspaces, users with the reader permission level are allowed to leave comments on workspace pages. You can check the "Disable commenting for readers" checkbox to block readers of your workspace from making comments on your pages.
Only users with classroom accounts or PBworks accounts can make comments on your workspace page.