How do you count the number of links in a chain? I thought this was a simple question but apparently there is some confusion - and it's good to have a basic question to refer people to. 

How many "links" are in these short bits of chain:

Image A (the original image for this question):





Image B:

Some people thought the bit of chain was too short and was missing a set of rollers, or wasn't in a loop. Here's a longer length of chain -- exactly twice as long as Image A, in fact. 



In your responses, try to make it clear whether you're referring to Image A or Image B.
Each set of "inner plates" is a link. Each set of "outer plates" is a "link." 

In the photo below  you can see two whole links.



Thus to answer the question, Image A in the question above has 4 links. Image B has 8 links.  

When you buy this box of chain that is labeled as having "120 links" and is standard 1/2" pitch, you should expect to get 60 inner links, 60 outer links, for a total of 120 links and it should measure 60" long:



Another way of thinking about links is that a "link" as a "place where a tooth goes" - thus if a chain wrapped completely around a 44 tooth chainring - it would have 44 links --  with 22 outer-plate-links and 22 inner-plate-links.


Another way to analogize is with a standard chain:



Everyone would agree that the standard chain image above has six links - each link creating one "hole".



Please note that there is a small but vocal group of people (including Sheldon Brown) who count a "complete link" as "one inner and one outer half-link". Counting "complete" links has the effect of halving the number of links (thus Image A would have 2 complete links, Image B would have 4 complete links, and that five foot length of SRAM chain would have 60 complete links).
Counting "complete" and "half" links as Sheldon does is non-standard at least as far as the industry is concerned. If someone starts talking about "complete" and "half" links when talking about chain length, you should clarify with them what they are talking about as you may end up with half or double the number of links you might otherwise expect.