Resource Buildings

What are Resources?
Resources are the currencies used to purchase and upgrade assets. In this game there are gold (Used to build most buildings and upgrade buildings), elixir (Used to train troops and build and upgrade some buildings) and gems (Used to accelerate building, training, upgrading and create Builder's Hut).

Gold
Gold is a currency in the game collected by Gold Mines, and kept in your Town Hall and Gold Storage. The amount of gold you have is displayed in the top right side of the screen. Gold is used to build Defensive Buildings, National Flag Decorations, and Elixir Collectors.

 Gold Mine

Elixir
Elixir is a currency collected by Elixir Collectors and stored in your Town Hall and Elixir Collectors. The amount of Elixir you have is displayed in the top right side of the screen under gold. Elixir is used for purchasing Troops, Army buildings and Gold related buildings.

 Elixir Collectors

Gems
Gems are a currency that costs real money and can be purchased within the game. Gems can be used to purchase Gold, Elixir, Builder's Hut, and to speed up upgrades, construction, and finish Training. In addition to money, Gems can be gained from clearing Obstacles, Tournaments, and Achievements.

It is best to keep all your gems for something important, eg: Speeding up constructions, Buying Gold and Elixir, Instant P.E.K.K.A training, Builder's Hut, upgrading town hall, etc. The gems were put in the game so that it would test your patience so you use real money to buy more gems for building and such, if you ignore and keep your gems it will only get worse, AKA if your impatient then this game is probably not a suitable game for you.