The Web is the software that makes up websites, applications, games, wikis, and videos that you can access on a web browser.

URL

Uniform Resource Locator
URL  =  DomainName.TLD/URI

URI

Uniform Resource Identifier

Domain Names

Domain names are organized from right to left, it means each label or section between the dots, specifies a subdomain of the section to its right. For example, in teamtreehouse.com, .com is the Top Level Domain, teamtreehouse is its subdomain

TLDs

.com .net .org .edu .us .ca .uk
Top Level Domains are considered a parent to domain names.

ICANN

TLDs are managed by the Internet Corporation for Assigned Names and Numbers, or ICANN.
ICANN authorizes domain name registrars.

Registrars

Domain name registrars are companies responsible for registering and reassigning domain names, companies like GoDaddy, NameCheap and many others.

IPv4

Nearly everything on the web uses Internet Protocol version 4, or IPv4 is comprised of four numbers, each between 0 and 255, separated by dots (e.g. 0.0.0.0 , 255.255.255.255, etc.). IPv4 has the capacity to identify about 4.3 billion unique addresses, but with over 7 billion people already on the planet and each person having more and more devices connected to the Internet, IPv4 is quickly running out of space.

IPv6

The new IP, Internet Protocol version 6 will support every person on Earth having billions of devices connected to the web at once.