A name server is a computer hardware or software server that implements a network service for providing responses to queries against a directory service. It translates an often humanly-meaningful, text-based identifier to a system-internal, often numeric identification or addressing component. This service is performed by the server in response to a service protocol request.
DigitalOcean provides these nameservers for free use. What you will need to do is modify the Domain nameservers at the control panel of your registrar and change these to DO:
If you run a whois after this, something like this should be the output;
Domain Name: EXAMPLE.COM
Registrar: ENOM, INC.
Whois Server: whois.enom.com
Referral URL: http://www.enom.com
Name Server: NS1.DIGITALOCEAN.COM
Name Server: NS2.DIGITALOCEAN.COM
Name Server: NS3.DIGITALOCEAN.COM
Now we need move into the DigitalOcean control panel.
Within the Networking section --> Domains , click on Add Domain, and fill in the the domain name field and IP address of the server you want to connect it to on the subsequent page. Note: The domain name does not have a www at the beginning.
After this you can create all your A,CNAME,SRV,TXT etc. records. If you got any more questions, don't hesistate to ask.