What does it mean to "link" my contacts? I just got an android today and I'm entirely lost with how it works. I was looking at my contacts and noticed the "link" option, so I tried it and clicked on another random contact, and nothing happened. What does the linking do exactly?
Well, I am sure you must be aware that Android shows your contacts from multiple sorces like Gmail, Facebook etc. 

I am sure you probably have the same contacts in multiple sources and LINK is a way of telling Android that these contacts, from the different sources, are same. Once you link the contacts Android will merge the contact details i.e. one contact will be shown with all the details from every source.