Giants are the 1st large troop that you get in your Barracks, and the 1st troop that can be upgraded to lvl 8. They start our fairly weak but as they advance in level they become one of the games super powers. They have a slow movement speed and slower attack but they are meant to be used in large groups

and under an assortment of spells that will speed them up. 

When traveling in groups they will blast their way

through walls and level defenses in a hurry. 

       Giants are a 5 housing space troop. They target

defenses until all defenses are destroyed. This

means that Giants have a couple of setbacks that

need to managed properly if you are going to have a

successful attack using them. 1st is that any troop

(both CC troops and Skeletons from the Skeleton Traps)

will be able to attack the

giants uncontested. They will not defend themselves until

all defenses are gone. This means that Giants can not

travel alone, they need other troops to watch their

backs! 2nd is if the village is designed with defenses

(like Hidden Tesla Tower) way off in the corners of

the map, the Giants will have a long way to travel at

their slow movement speed to clear the map of all of

the defenses.This will cost you  a 3 star attack if not

planned for

ahead of time.

      Giants are best used on the front line as "meat

shields", absorbing all of the defensive firepower as

their counterpart troops come in behind them and level

the village. A very popular Giant attack consists of a

large horde of Giants with several Healers floating over

their shoulders, frantically healing them as they plunder through the village. The Giants are also a popular replacement to the costly Golems in the Gowipe (Golem,Wizard and P.E.K.K.A.) Gowiwi (Golem, Wizard and Witch) and the vamped up Govape (Golem, Valkyrie and PEKKA) when farming to reduce the use of the Dark Elixer. 

       Overall, for the cost, the training time and for the value you will get from them, the Giants should be at the top of your troop list. They are cheap, fast to train and tough as nails when used properly.

       One last thing I feel like I have to mention, I have watched players from Damage Inc. get 3 star attacks while doing farm raids with Giants (in combination with other troops of course) at all TH levels of the game. They are not just the cheaper alternative to Golems anymore. In fact if your clan was to face a clan from China in your next Clan War I would bet that at least one out of 10 players from their clan will attack with Giants as their tanks.. seen that 100s of times from the China clans!