Why does my defense keep losing in Clash of Clans?

If you are upgrading your town hall before upgrading your defenses to the maximum, your chances of losing against an attacker will become higher.

Walls are extremely important in helping your defenses win. Make sure you upgrade your walls to the maximum before upgrading your Townhall. See also how to reduce attacks on your village.

Upgrading air defences is very important because some players use dragons and air units as the majority of their army. When they find weak air defenses, those players easily wipe out bases. See also how to make a successful attack.

Even if your defenses are strong, you can still lose against an attacker if your village isn't laid out properly. Learn from other players by watching what they do in order to come up with a suitable layout.

When you advance to higher leagues, expect stronger players to attack your base. It's always a good idea not to advance to a certain league before you make sure you are strong enough to compete there. See also how to level up fast.

Splash defenses, such as Towers and Mortars, do a lot of damage to large groups of enemies. If you don't upgrade your splash defenses fully, your chances of losing will become higher.

If an attacker destroyed your Townhall, they will win the attack even if they don't do anything else. Your Townhall must be well protected to make it harder for people to win. See also how to get free gems.

Castle troops can make a significant difference and help you destroy large armies fast. Make sure you have castle troops in your castle if your defenses lose often. See how to defeat castle troops.

When you place your defenses far apart from each other, you make it easier for an attacker to take them down. The closer the defenses to each other, the harder it is to destroy them. See also how to protect your resources in Clash of Clans.

In order for your defenses to win, you need to make sure that any point of the map is covered by Mortar fire, ground defenses and air defenses. If the balance isn't maintained, an attacker might easily exploit this missing gap using the proper unit.

If your base is surrounded by a single wall and all of the buildings are placed inside, you might easily lose. Make sure there are more than one level of walls arranged in such a way that an attacker has to break through many ones in order to reach the important buildings.

If you store too much Gold or Elixir, you might be attracting strong players to your base. Make sure you design your base and manage your resources in such a way that you don't attract strong players to you.