What variables do

A variable is a placeholder in a template that gets replaced with each prospect's data at send time. #{{first_name}} becomes Sarah for Sarah and Miguel for Miguel.
Inserting variables
Use the Variables inserter in the template editor — it lists every field available to you: standard fields (name, company, title, city, website, and so on), the Snippet fields, and your account's custom fields.
Available fields include
- Contact basics: first/last name, email, company, industry, title, phone, city, state, address, website.
- Snippet, Snippet 2, Snippet 3, Snippet 4 — your per-prospect personalization lines (see Snippets and custom fields in templates).
- Custom fields defined in your account.
Rules that keep sends safe
- Never personalize a subject line on data you might be missing — a blank variable in a subject looks like a broken mail-merge.
- Double-check spelling of the variable against the inserter; a typo won't resolve.
- Keep fallbacks in mind — write openers that still read sensibly if the field is empty, or fill snippets for every prospect before they enter the campaign.