Clash of Clans. A game that must be installed on your mobile phone

Clash of Clans is a popular iPad/iPhone/iPod/Android game created by "Supercell". It has been available internationally on the iTunes store for free since its initial v1.7 release on 2 August 2012, and on the Google Play Store since 8 October 2013. From rage-filled Barbarians with glorious mustaches to pyromaniac Wizards, raise your own army and lead your clan to victory! Build your village to fend off raiders, battle against millions of players worldwide, and forge a powerful clan with others to destroy enemy clans.

 Defensive buildings:

                                -Cannon:

"Cannons are great for point defense. Upgrade cannons to increase their firepower, but beware that your defensive turrets cannot shoot while being upgraded!"

• Cannons are the first defensive structure that a player builds at the start of their Clash of Clans adventure. 
• Cannons are both cheap and quick to upgrade at lower levels.
• Cannons can shoot any ground units, such as Barbarians, but not any air units, such as Dragons, balloons, etc. 

             -Wizard Tower:

"The Ultimate Arcane Defense! Tower Wizards cast powerful area effect spells that target both flying and ground troops."

• The Wizard Tower is a spiraling, cone-shaped tower of crystalline rock that has a Wizard atop it. It is capable of inflicting powerful splash damage to both Ground and Air Units, though it is limited to a relatively short range.
• The Wizard Tower, like the Mortar, excels at mowing down entire groups of Troops. However, unlike the Mortar, it has a relatively decent DPS (making it more effective against higher health troops like Giants), and it will target Air Troops in addition to Ground Troops. Also unlike the Mortar, the Wizard Tower has no blind spot.
• Although the arcane blasts from the Wizard Tower do less damage per shot than Mortar, it makes up for this by having a much higher rate of fire. This makes the Wizard Tower an excellent choice for defending other structures by blasting troops that get too close. The Wizard Tower's only real weakness is its range, which is among the lowest of all defensive structures.
• Taking out Wizard Towers can be tricky despite their relatively short range. It is often a better tactic to avoid them entirely by attacking a part of the village that isn't covered by them. To quickly destroy a Wizard Tower, deploy a few Giants as a distraction while Archers, Wizards or Minions take out the tower. Deploy Troops in a circle around it since this will limit its ability to take out multiple troops with splash damage. Dropping 1 Giant and surrounding the tower with 5 Archers will generally be sufficient to destroy it. 

          -Archer tower:

 "Archer Towers have longer range than cannons, and unlike cannons they can attack flying enemies.''

• Archer Towers are extremely versatile structures. They are able to target both Ground and Air Units, and they have excellent range. This versatility means that they should form the cornerstone of every player's defense. 

• Archer Towers can target both Ground and Air Units at an amazing distance. Therefore, it is generally a good idea to place them on the outer perimeter of the village. Doing so allows players to capitalize on the excellent range and provides good coverage for the rest of the defenses.
• As Archer Towers have the ability to target both Ground and Air Units, a good strategy would be to place all of the other defenses within range of at least one Archer Tower.
• It is typically a good idea to upgrade Archer Towers before you upgrade Cannons. Although they are more expensive and take longer to upgrade than similar-level Cannons, Archer Towers have more range and can target air units as well as ground units.
• It is typically wise to put an Archer Tower near a Cannon or Mortar due to the fact that neither of these two defenses can target air units.

            -Mortar:

"The Mortar can mow down hordes of enemies by the splash damage from its shell. Don't let enemies get too close to it!"

• Mortars are the player's heavy defenses. Whenever an enemy comes into range, it blasts out an explosive shell with a low frequency "ping".
• Mortars shoot long-range explosive shells every 5 seconds which deal devastating splash damage to every unit within a small radius of the impact point. Their splash damage, combined with their long range, make them deadly weapons against large groups of weaker enemies such as Barbarians, Archers, or Goblins.
• A Mortar's major disadvantages are its inability to attack troops within 4 tiles, its low rate of fire and low DPS which makes them less effective against high-health troops.
• Due to the fact that the Mortar's shell takes a while to reach its target (over a second at maximum range), fast troops like Goblins can easily dodge its attack if they are moving when the Mortar fires.
• Mortars cannot target air troops. 

You can see a lot of information in: http://clashofclans.wikia.com