Hi there! well to have fully operational website you need 2 things:
1) Domain name
2) Hosting space
Most of the hosting companies will offer 1st year of domain registration for free with hosting, so it makes sense to host the domain with the same company if you want to save about $10.
The only downside is if you decide to move to another hosting provider, most of the hosting companies will make it extremely difficult for you to transfer the domain elsewhere. So for the flexibility I host all my domains at the single register like GoDaddy (GoDaddy is only good for domain names, hosting is bad there) and then buy hosting with another provider (anybody from this list is great: https://webhostinggeeks.com/besthosting.html
) . Then just point the domain's DNS at GoDaddy to any hosting company.
Hope this helps.