diff --git a/world/blocks.md b/world/blocks.md
index d9615ad..0d48b47 100644
--- a/world/blocks.md
+++ b/world/blocks.md
@@ -28,7 +28,13 @@ instance.setBlock(0, 41, 0, tnt);
 
 ## Registry
 
-Each block has unique data which can be retrieved with `Block#registry()`.
+Each block is associated with a `BlockEntry`,which store some **unmodifiable **(not immutable) data generated by **vanilla**.
+
+For example, `BlockEntry#explosionResistance()` return the explosion resistance in vanilla,and it's unmodifiable.However,it is just a value and will not really affect the explosion.
+
+`BlockEntry` is unmodifiable for now, though we plan to make it modifiable in the future.
+
+`BlockEntry` can be retrieved with `Block#registry()`.
 
 ```java
 Block block = Block.GRASS;