Cname and Dns Actions

I am trying to get how DNS works. I've seen some videos and schemas that explain how DN Servers work. But I didn't understand the role of the CNAME record. What happens when eventually my authoritative name server gives the exact IP address for the website I am searching for and what does CNAME do meanwhile? At my domain provider, it's standing for pointing 'www' subdomain to my Cname which is provided from my host server. (sm. like web-23242.hostsw.com). And also when I type this to the address bar there are not any results.So what does cname do inside these dns interactions?