A Never Ending Chain is a chain of buildings designed to delay monsters.
Types of Never Ending Chains
There are 4 types of Never Ending Chains, though one of them makes your base a superfarm.
Never Ending Chain (NEC)
The most common type of the Never Ending Chain is one made from lootless and non-defending buildings, and is simply called Never Ending Chain due to it's popularity.
Never Ending Chain of Resource Gatherers (NECoRG)
Never Ending Chain of Towers (NECoT)
When used right, this NEC can help stall monsters and increase CF. A ring of unprotected towers will lead to a farm base, though.
Never Ending Chain of Silos and Town Hall (NECoSaTH)
Do not use this unless you wish to serve as no more than a farm. Since the Townhall and Storage Silo's are the buildings that give resources, why would you put them where others can easily attack?