Merge tag
A placeholder in the email that is replaced with the recipient’s own data on send.
A merge tag is a marker such as `{{first_name}}` that the sending platform swaps for real data as each message goes out. It is what makes one template address a thousand people by name.
The syntax belongs to the platform, not to email: Mailchimp, Klaviyo and HubSpot each write them differently, which is why a template moved between platforms usually needs its tags rewritten.
Always set a fallback. A greeting that reads “Hello ,” is the classic sign of a merge tag meeting an empty field.