The “www” is a subdomain

When it’s the default “www”, it means that it’s the root or main website. But it can also be set as a different name, such as drive.google.com or chat.google.com, for example. These subdomains are treated as different websites entirely.

So drive.google.com is another website for all intents and purposes to www.google.com. Usually, you can drop the “www” and it will be understood as such.

A website can have directories, which are sort of folders, such as mail.google.com/chat and mail.google.com/mail. 

These take the user to different parts of the Gmail website, namely the chatting and email systems. This works as a way to organize the content.

Finally, the last part of the content is the slug or path, such as blog.google/technology/ai/ways-ai-is-scaling-helpful.

Do you notice? There are two subdirectories, technology and AI. Probably, AI is nested inside Technology. The slug is “ways-ai-is-scaling-helpful”.