Farming 101

This guide is only to explain what farming is and how it works.

Farming in Clash of Clans is essentially the process of raiding only for resources (gold, elixer and dark elixer). Farming is a technique that grants you maximum theft of those resources instead of attacking for trophies. In most cases, players will intentionally lose battles, as to not gain any trophies. Usually, the farming player will lose multiple battles in order to lower their trophy count, so they can attack weaker players. Please note, that dropping too low in trophies, could make it difficult to find good resources.
So why farm? Well if you don't have hundreds of dollars to spend on gems to get stuff upgraded, quickly getting resources to pay for those upgrades is the main reason. If you do have gems, use those to speed up the upgrade, not to pay for the upgrade.
There are specific strategies for attacking and defending which will allow maximum profits and decrease losses from enemy attacks. These strategies will be explained in future guides.
Also take note that town hall levels play a big part in any attack, but especially in farming. Lets say that you have a level 7 town hall. Now if you try to attack someone of the same town hall level, you will be able to loot 10% of the resources. If you are attacking someone lower than you, lets say town hall level 6, you will only be able to get 5%. And in reverse, if you're going after someone with a town hall level 8, you will get 15%. The more levels between your town hall and the person you are attacking, the more the resources will increase or decrease.
Again, please note that this is not a guide or technique to gaining trophies or wining battles, only for gaining resources.
There are more guides which will address specific tactics. I did not want to put everything in one giant forum, so I am splitting it up so it is easier to read.