Why is a website hosting provider important?
A website hosting provider is essential in order to connect a website to the internet. The website hosting provider takes care of hosting the domain name and makes sure the website is available on internet by entering the IP addresses in the DNS server. Especially with new websites it's customary for the website hosting provider to take over these tasks.
Larger, more developed websites tend to keep these tasks under the management of the client. Large businesses have their own DNS servers and manage the IP blocks where their website is addressed.