What It Is
An A record, short for address record, links a domain name to an IPv4 address, the familiar style of IP address written as four numbers separated by dots. When someone types your domain, the A record tells their browser which server to go to. It is like the street address on file for your business.
Why It Matters for Your Business
The A record is usually what changes when you move your website to a new host. Your new host gives you an IP address, and you update the A record to match. A contractor launching a new site might have the old site still showing for a while, simply because the A record has not been updated or the change has not spread yet.
Good to Know
You typically need A records for both the bare domain (yourbusiness.com) and the www version, or a CNAME for www pointing to the main domain. Leaving one out means some visitors reach the site and others see an error. Test both versions in a browser after any change.