A relationship can be set between any 2 records in the CRM. New relationship types can be created if you have the correct level of authority in the CRM. In the example shown in this article, we'll set it between a Contact and a Company. 

On a Contact, select the Related page on the left-hand side. This will show you any existing relationships which have been set up and also allow you to create new ones. 

To create a new relationship, select the plus icon which will open the new window shown below. The example below shows the 'Configure' option, this is only available if you have CRM Admin rights.

Once you've selected the correct relationship, you then need to select the record you want to link to. Depending on the type of relationship you've selected, it will alter the search you are able to complete. For example, if the relationship goes from a Contact to a Company, then the search will only return Companies for you. 

Once you've chosen the correct record, the new relationship will be shown on the Related page. 

If you open the corresponding record from the Related tab, you'll see the same relationship displayed.