diff --git a/src/main/java/org/kapelle/multiblock/BlockComponent.java b/src/main/java/org/kapelle/multiblock/BlockComponent.java
index c8bf6d2..a9870ab 100644
--- a/src/main/java/org/kapelle/multiblock/BlockComponent.java
+++ b/src/main/java/org/kapelle/multiblock/BlockComponent.java
@@ -8,6 +8,11 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
 
+/**
+ * Represents a single position in a multiblock.
+ * Can be a single type of block or multiple types.
+ * Custom valid check functions are supported,
+ */
 public class BlockComponent {
     private final BlockComponentMode mode;
     private final Set<Material> blocks;
diff --git a/src/main/java/org/kapelle/multiblock/ICheckFunction.java b/src/main/java/org/kapelle/multiblock/ICheckFunction.java
index cfaddf5..b25baf3 100644
--- a/src/main/java/org/kapelle/multiblock/ICheckFunction.java
+++ b/src/main/java/org/kapelle/multiblock/ICheckFunction.java
@@ -2,6 +2,9 @@ package org.kapelle.multiblock;
 
 import org.bukkit.Location;
 
+/**
+ * Interface for a custom check function.
+ */
 public interface ICheckFunction {
     boolean apply(Location location);
 }
diff --git a/src/main/java/org/kapelle/multiblock/MultiblockListener.java b/src/main/java/org/kapelle/multiblock/MultiblockListener.java
index 7dc5390..c7de236 100644
--- a/src/main/java/org/kapelle/multiblock/MultiblockListener.java
+++ b/src/main/java/org/kapelle/multiblock/MultiblockListener.java
@@ -7,6 +7,9 @@ import org.bukkit.event.block.BlockPlaceEvent;
 import org.bukkit.plugin.java.JavaPlugin;
 import org.bukkit.util.BlockVector;
 
+/**
+ * Listens for block placements and checks if it is part of a the multiblock structure.
+ */
 public abstract class MultiblockListener implements Listener {
     private final BlockComponent coreBlock;
     private final BlockVector coreBlockOffset;
@@ -31,6 +34,10 @@ public abstract class MultiblockListener implements Listener {
         }
     }
 
-    abstract void callback(Location coreBlockLocation);
+    /**
+     * Gets called on successfully validating a multiblock
+     * @param coreBlockLocation location of the core block
+     */
+    protected abstract void callback(Location coreBlockLocation);
 
 }
diff --git a/src/main/java/org/kapelle/multiblock/MultiblockStructure.java b/src/main/java/org/kapelle/multiblock/MultiblockStructure.java
index b76dd3b..dc87ba4 100644
--- a/src/main/java/org/kapelle/multiblock/MultiblockStructure.java
+++ b/src/main/java/org/kapelle/multiblock/MultiblockStructure.java
@@ -5,10 +5,20 @@ import org.bukkit.util.BlockVector;
 
 import java.util.List;
 
+/**
+ * Represents a full multiblock.
+ * Contains the individual block components.
+ */
 public class MultiblockStructure {
 
     List<List<List<BlockComponent>>> structure;
 
+    /**
+     * Create a multiblock structure.
+     * The format is like this: [y][z][x]
+     * So you describe the layers from bottom to top.
+     * @param structure structure in the format: [y][z][x]
+     */
     public MultiblockStructure(List<List<List<BlockComponent>>> structure){
         this.structure = structure;
     }
@@ -21,6 +31,12 @@ public class MultiblockStructure {
         return structure.get(y).get(z).get(x);
     }
 
+    /**
+     * Checks if the multiblock is valid at the given location.
+     * @param location Location of a block in a multiblock structure.
+     * @param offset the offset of the location from <0,0,0>
+     * @return true if valid
+     */
     public boolean isValid(Location location, BlockVector offset){
         for (int y = 0; y < structure.size(); y++) {
             for (int z = 0; z < structure.get(y).size(); z++) {