Have you ever visited a site and thought -
Wow, I really like that. I wonder what they used to make it ?
In the past it was easy to find out: just right click on the page and then click "view source".
From there you could scroll down and easily see if it was html, WordPress, Java, or any other code. You could even copy some of the code snippets to use on your own site if you wanted.
This can still be done but websites are much more complex these days and quite often harder to decipher.
Luckily there are now tools available to help you out. Just do a search for "how to tell what a website was created with" and you can easily find browser addons, software, and even free sites that allow you to enter a URL and give you all the details.
They are free for the casual user and provides a great deal of information. It will tell you the web hosting provider (important to know if certain features are needed), what it was created with (WordPress, Drupal, HTML, Java, etc.), the Content Management System it is using (if any), Social Media links, Advertising Info, Analytics and Tracking, Payment Providers, Secure Certificate Info, Shopping Carts used, and much more. As video becomes more popular be sure and take a look at what is used to embed video on the site and find out which ones load fast (or not) and have the embedded controls you desire.
So- the next time you see a website you like go ahead and take a deeper look.
It's Easy !