A global merge field type to use when
referencing information about the current user. User merge
fields can reference information about the user such as alias,
title, and ID.
Usage
Use dot notation to access the current
user’s information. For example:
{!IF (CONTAINS($User.Alias, Smith) True, False)}
Example
The following example displays the
current user’s company name, as well as the status of the
current user (which returns a Boolean value).
<apex:page>
<h1>Congratulations</h1>
This is your new Apex Page
<p>The current company name for this
user is: {!$User.CompanyName}</p>
<p>Is the user active?
{!$User.isActive}</p>
</apex:page>