A merge field is a field you can put in an email template, mail merge template, custom link, or formula to incorporate values from a record.
Required Editions
| Available in: Salesforce Classic and Lightning Experience |
| Available in: Contact Manager, Group, Professional, Enterprise, Performance, Unlimited, and Developer Editions |
Visualforce pages use the same expression language as formulas—that is,
anything inside {! } is evaluated as an
expression that can access values from records that are currently in context. For
example, you can display the current user's first name by adding the {!$User.FirstName} merge field to a
page.
<apex:page>
Hello {!$User.FirstName}!
s</apex:page>If your user’s name is John, the page will display Hello John!
You also can use merge fields or other functions to personalize your object-level help content.