Basic Liferay terms and concepts

Instance - This does not refer to "a given Liferay installation" on a server. If you check the control panel under the "Server" section, you will see "Portal Instances" -- a single installation can run multiple instances of the portal.

Virtual Host - A virtual host allows a portal instance to use a domain name or multiple domain names. This can be used to serve pages directly from /web/guest or from another community or organization. For example, you might have a server ip of 555.555.55.555, and your site runs at 555.555.55.555/web/guest by default. Using a virtual host, you can configure Liferay to run from http://www.mysite.com (and even omit the /web/guest).

Community - A community is formed by:

A set of users: which are called members and which can be given different permissions within the community by assigning them 'Community Roles'

A set of public and private pages: the private pages will only be seen by members while the public pages are visible to anyone. It's optional for each community to have either public pages, private pages, both or none.

A set of permissions: that all of its members will inherit.

By default Liferay provides a community called 'Guest' plus a personal community for the administrator. The 'Communities' portlet can be used to create as many communities as desired.

Organization - This is another grouping within Liferay.  Functionally, it is very similar to Community.  However, it has 2 main differences.  First, you cannot share content between organizations.  If you need share content between groups, use communities.  Secondly, you can nest organizations.  One parent can have many children.

For example, if you have XYZ, Corporation as the parent organization, this will include everyone from the night janitor to the CEO.  Within the XYZ Corporation, you might have HR, Manufacturing, Sales, and Distribution organizations as children organizations of XYZ corp.

User Group - The third entity is User Groups.  This refers not just to groups of users but to pages that are created for them  User group pages are added to the personal pages of each user but are maintained in a central location.  This allows for individual administration of group pages.  User Group pages lack the "Settings" tab which allow you to export site maps as well as do things like use a virtual host there.

Plugins - Plugins include portlets, themes, hooks, layouts, and web plugins. You can create plugins using the Plugins SDK

Default User and Password - For a Liferay installation, the default login credentials are:

username: test@liferay.com
password: test

However, starting in 5.2.x - 6.0.x and forward, if you have the 7Cogs dummy data in your install (default), then your login credentials are

username: bruno@7cogs.com
password: bruno

If you have removed the 7Cogs data or installed without it, then your username should be back to

username: test@liferay.com
password: test