What is the difference between 0.0.0.0, 127.0.0.1 and localhost?

Question

I am using Jekyll and Vagrant on my mac. I found that Jekyll server will bind to 0.0.0.0:4000 instead of 127.0.0.1:

Answer 1

In current version of Jekyll, it defaults to http://127.0.0.1:4000/.
This is good, if you are connected to a network but do not want anyone else to access your application.

However it may happen that you want to see how your application runs on a mobile or from some other laptop/computer.

In that case, you can use

jekyll serve --host 0.0.0.0

This binds your application to the host & next use following to connect to it from some other host

http://host's IP adress/4000