How do I show related content?
Creating a related content view in Drupal 7:

Show related content based on shared Term-pages (from any given vocabularies).

Each term page will be recognized by the term ID (TID) hidden in the pages’ URL.

The process:

Basic stages:


Create a “Content” view-block.
Add a contextual filter: “Has taxonomy term ID”.
Choose “provide a fixed value”.
(From type): “Taxonomy term ID from URL“.


Checking:

•   Uncheck “Load default filter from the term page”.
•   Check “Load default filter from node page, that’s good for related taxonomy blocks”.

•   Check “Limit terms by a vocabulary”.
•   Check your desired vocabulary.


Select “Filter to items that share any term”.
Go down and check “Reduce duplicates”: This will several terms that relate to the same page – To appear. Only one will of them will.


https://www.daymuse.com/blogs/drupal-guide-related-content-term-views

Optional:

If you would like that the current node won’t appear in the list:


Go to the view and add another, extra Contexutal filter.
Give it content: NID.
Select “Provide default value”.
Set the “Type” to “Content ID from URL”.
Go down in that window, click on “More”, and there check “Exclude”.


Note that this will exclude the current node in which the related is shown – From that very list.

It will do so by using the content ID which is a (hidden) part of the URL.