what are different major services of the internet?

[vivian fe]

[Zarn]

Depends on how you define "major", "service" and "internet". Some quite common and important functions would be DNS resolution (and by extension, DNS) and addressing through IANA, ICANN or other authority that can assign /8 IP v4 address blocks. There's also various transport and addressing work, but the national registrars are probably the most important / most "major" when it comes to handling DNS stuff.