A zone file is a text file used in the Domain Name System (DNS) to map domain names to IP addresses and other resources. It contains a series of records such as A, CNAME, MX, and TXT records that define how queries for a specific domain or subdomain should be handled. Each zone file is associated with a particular DNS zone, typically representing a single domain and its subdomains. Proper configuration of a zone file is essential for ensuring that internet traffic is correctly routed to websites, email servers, and other online services.