OpenDNS Instead of the ISP for DNS Service

I was wrestling with networking problems in Windows 7, when I came across this quotation on the OpenDNS website:

Rid your household of annoying, intermittent Internet outages. Switch to OpenDNS and immediately notice a faster, more reliable Internet experience. Join the millions who've already unbundled their DNS service from their ISP's Internet connection.

I had not realized that the two could be separated.  For that matter, I really had no idea what DNS service was.  But OpenDNS was free, so I signed up.  I went to their settings page.  In essence, they told me to go to Control Panel > Network and Sharing Center > Change adapter settings > double-click on Local Area Connection > highlight TCP/IPv4 > Properties > Use the following DNS server addresses > Preferred DNS server = 208.67.222.222, Alternate = 208.67.220.220.  (The default setting there was "Obtain DNS server address automatically.")  It wasn't in their instructions, but I clicked "Validate settings upon exit" before clicking OK and closing out of there.  This ran Windows Network Diagnostics, which said, "Troubleshooting couldn't identify the problem."  So that sounded good.  OpenDNS then gave me a webpage where it said, "Success!  You're now using OpenDNS."

I really had no idea what this meant.  But it seemed to be the solution to a part of a cluster of networking problems I was having at this time, as described in other posts in this blog.  So I was happy about that.