Also known as an address or host record, A is a type of DNS entry or resource record that points a domain or subdomain to an IP address. An A record is the simplest type of DNS record but one of the most critical records of your domain name.
An A record contains the IP address of the host computer (or hostname) that you want to be associated with your domain name.
If you have a website hosted on a server somewhere off-site from where your domain name is registered, that is where the A record will be pointing towards.
For example,
www.google.com is what you type to get to the google search bar. The IP address (74.125.224.147) is pointed to by an A record on google’s nameserver. When you go to www.google.com in your browser, the request goes to the server with the IP address (74.125.224.147). People can connect to a website using easy-to-remember domain names instead of hard-to-remember IP addresses.