diff --git a/crates/sapphire-ecr/lib/index.d.ts b/crates/sapphire-ecr/lib/index.d.ts
index b20f09e..137a65c 100644
--- a/crates/sapphire-ecr/lib/index.d.ts
+++ b/crates/sapphire-ecr/lib/index.d.ts
@@ -32,6 +32,92 @@ export interface spawner<T> {
     spawn_with_handle(...components: T[]): Handle;
 }
 
+export type raw_data = Map<Entity, Map<number, any>>;
+
+/**
+ * A replicator keeps track of all entities with the passed components and their values -
+ * whenever a component is changed (add, change, remove) and the replicator listens to it, it's also changed within the contained raw data.\
+ * The developer can then calculate the difference on the server and send it to the client every time,
+ * on which the difference is then applied to the registry.\
+ * Albeit it's called a replicator, it doesn't replicate the data by itself.
+ * It allows the developer to use any networking libary to replicate the changes.
+ * ```ts
+ * // server
+ * const replicator = sapphire_ecr.create_replicator(component_a, component_b, ...)
+ *
+ * export function system() {
+ *     return () => {
+ *         const difference = replicator.calculate_difference() --> buffer
+ *         // There might not be any difference
+ *         if (!difference) return
+ *         data_replication_event.send_to_all(difference)
+ *     }
+ * }
+ * ```
+ * ```ts
+ * // client
+ * const replicator = sapphire_ecr.create_replicator(component_a, component_b, ...)
+ *
+ * export function system() {
+ *     return () => {
+ *         for (const [_, difference] = data_replication_event.poll()) {
+ *             replicator.apply_difference(difference)
+ *         }
+ *     }
+ * }
+ * ```
+ */
+export interface replicator {
+    /**
+     * Gets the full data representing the entire registry.
+     * Useful for initial replication to every player.
+     * ```ts
+     * const replicator = sapphire_ecr.create_replicator(component_a, component_b, ...)
+     *
+     * Players.PlayerAdded.Connect((player) => {
+     *     data_replication_event.send_to(player, replicator.get_full_data())
+     * })
+     * ```
+     * @returns raw_data
+     */
+    get_full_data(): raw_data;
+    /**
+     * Calculates the difference between last sent data and currently stored data.
+     * ```ts
+     * // server
+     * const replicator = sapphire_ecr.create_replicator(component_a, component_b, ...)
+     *
+     * export function system() {
+     *     return () => {
+     *         const difference = replicator.calculate_difference() --> buffer
+     *         // There might not be any difference
+     *         if (!difference) return
+     *         data_replication_event.send_to_all(difference)
+     *     }
+     * }
+     * ```
+     * @returns raw_data?
+     */
+    calculate_difference(): raw_data | undefined;
+    /**
+     * Applies the difference to the current data.
+     * ```ts
+     * // client
+     * const replicator = sapphire_ecr.create_replicator(component_a, component_b, ...)
+     *
+     * export function system() {
+     *     return () => {
+     *         for (const [_, difference] = data_replication_event.poll()) {
+     *             replicator.apply_difference(difference)
+     *         }
+     *     }
+     * }
+     * ```
+     * @param difference raw_data
+     */
+    apply_difference(difference: raw_data): void;
+}
+
 declare interface WorldDeclaration {
     readonly identifier: "sapphire-ecr";
     readonly methods: Map<string, (singleton: singleton) => void>;
@@ -42,9 +128,64 @@ declare interface WorldDeclaration {
     readonly render_stepped_systems: system[];
 
     extension(): void;
+    /**
+     * Creates a spawner.
+     * ```ts
+     * const spawner = sapphire_ecr.create_spawner(components.part, components.velocity, components.part)
+     * for (let i = 0; i < 1000; i++) {
+     *     spawner.spawn(part_template.Clone(), Vector3.zero, Vector3.zero)
+     * }
+     * ```
+     * @param components T[]
+     * @returns spawner<T>
+     */
     create_spawner<T>(...components: T[]): spawner<T>;
+    /**
+     * Creates an entity and returns its id.
+     * @returns Entity
+     */
     spawn_entity(): Entity;
+    /**
+     * Creates an entity and returns a handle to it.
+     * @returns Handle
+     */
     spawn_entity_with_handle(): Handle;
+    /**
+     * Creates a `replicator`.
+     * A replicator keeps track of all entities with the passed components and their values -
+     * whenever a component is changed (add, change, remove) and the replicator listens to it, it's also changed within the contained raw data.\
+     * The developer can then calculate the difference on the server and send it to the client every time,
+     * on which the difference is then applied to the registry.\
+     * Albeit it's called a replicator, it doesn't replicate the data by itself.
+     * It allows the developer to use any networking libary to replicate the changes.
+     * ```ts
+     * // server
+     * const replicator = sapphire_ecr.create_replicator(component_a, component_b, ...)
+     *
+     * export function system() {
+     *     return () => {
+     *         const difference = replicator.calculate_difference() --> buffer
+     *         // There might not be any difference
+     *         if (!difference) return
+     *         data_replication_event.send_to_all(difference)
+     *     }
+     * }
+     * ```
+     * ```ts
+     * // client
+     * const replicator = sapphire_ecr.create_replicator(component_a, component_b, ...)
+     *
+     * export function system() {
+     *     return () => {
+     *         for (const [_, difference] = data_replication_event.poll()) {
+     *             replicator.apply_difference(difference)
+     *         }
+     *     }
+     * }
+     * ```
+     * @returns replicator
+     */
+    create_replicator(): replicator;
 }
 
 /** @readonly */
diff --git a/crates/sapphire-ecr/lib/init.luau b/crates/sapphire-ecr/lib/init.luau
index 3b7c0fa..d60ab39 100644
--- a/crates/sapphire-ecr/lib/init.luau
+++ b/crates/sapphire-ecr/lib/init.luau
@@ -95,7 +95,7 @@ end
 --- ```luau
 --- local spawner = sapphire_ecr.create_spawner(components.part, components.velocity, components.position)
 --- for _ = 1, 1000 do
----     spawner.spawn(part_template:Clone(), Vector3.new(0, 0, 0), Vector3.new(0, 0, 0))
+---     spawner.spawn(part_template:Clone(), Vector3.zero, Vector3.zero)
 --- end
 --- ```
 --- @param ... T... -- Components to use.
@@ -104,7 +104,7 @@ function SapphireEcr.create_spawner<T...>(...: T...): spawner<T...>
     return create_spawner(...)
 end
 
---- Creates an entity and returns it's id.
+--- Creates an entity and returns its id.
 --- @return ecr.entity
 function SapphireEcr.spawn_entity(): ecr.entity
     return SapphireEcr.registry:create()
@@ -148,7 +148,7 @@ export type raw_data = {
 ---
 --- function singleton.system()
 ---     return function()
----         for _, difference in data_replication_event.poll()
+---         for _, difference in data_replication_event.poll() do
 ---             replicator.apply_difference(difference)
 ---         end
 ---     end
@@ -227,7 +227,7 @@ export type replicator = {
 ---
 --- function singleton.system()
 ---     return function()
----         for _, difference in data_replication_event.poll()
+---         for _, difference in data_replication_event.poll() do
 ---             replicator.apply_difference(difference)
 ---         end
 ---     end