SharePoint Group - Site Visitor (Read)

When a SharePoint site is created, by default 3 SharePoint groups are created

Site Owners - Full control

Site Members - Contribute

Site Visitors - Read

Below are the permissions you get when you are a Site Visitor (Read)

List Permissions

View Items - View items in lists and documents in document libraries.

Open Items - View the source of documents with server-side file handlers.

View Versions - View past versions of a list item or document.

Create Alerts - Create alerts.

View Application Pages - View forms, views, and application pages. Enumerate lists.

Site Permissions

View Pages - View pages in a Web site.

Browse User Information - View information about users of the Web site.

Use Remote Interfaces - Use SOAP, Web DAV, the Client Object Model or SharePoint Designer interfaces to access the Web site.

Use Client Integration Features - Use features which launch client applications. Without this permission, users will have to work on documents locally and upload their changes.

Open - Allows users to open a Web site, list, or folder in order to access items inside that container.