Basically, a HTTP client contacts a HTTP server with an IP address. For example, when you access google.com, your web browser could be using 126.96.36.199 as the IP address to contact one of Google’s web servers. Although an IP address is what HTTP clients used for contacting HTTP servers, a domain name is easier to remember.
So if you want to host a web server at home, it is recommended that you get a domain name to make accessing your web server easier. In case you are looking for a domain name registrar to purchase a domain for your home server, this post discusses why you may want to buy from Namecheap.