.onion domain what is it and how to enter it?

If you find a website ending in .onion and after you clicked the link an error page appeared.
That happened because you probably do not have the Tor browser installed on your system.
you can read how to install the Tor browser in this post:
http://www.securityfreak.info/security/using-and-testing-tor-browser-for-the-first-time
With everything installed and running, now you can open you .onion link on your Tor browser.

But .onion domain what exactly is this?
A .onion is a top level domain just as .com or .net, with the difference it is not spread through the regular Internet dns system, instead it uses the Tor proxy to protect the privacy from both the publishers and it's users!
You can read all the details in the wikipedia link: https://en.wikipedia.org/wiki/.onion

but there is not much more to it. .onion domain in a nutshell, is a top level domain allocated in the Tor network that must be accessed through the Tor network.
You can find 10 good .onion websites in this post http://www.securityfreak.info/tips/10-deepweb-pages-and-its-description-onion-link/ with topics ranging from Cat trivia to hired assassination services :)

We also offer you several .onion links on the right panel of your browser from posts that I already made on this blog.
I hope I was clear with this post, any questions do not hesitate to leave as a comment, thanks.