Files, databases, email directories, server configurations, and TLS certificates. Roughly:
Files — everything in your web root (source code, themes, uploads, plugins) plus any custom application paths you specify.
Databases — full SQL dumps of MySQL and PostgreSQL. Consistent snapshots, so no half-committed transactions.
Email — mail directories on Pro and Business tiers. Not included on Essential — speak to us if you need email-only backups separately.
Server configs — nginx, Apache, .htaccess, DNS records, cron jobs. Small in size, absolutely vital for fast recovery.
TLS certificates — certs and private keys. So restored sites come back with HTTPS already configured, not needing a fresh cert issuance.
See the Process section above for the full archive structure and typical sizes.