diff --git a/src/items/items.service.ts b/src/items/items.service.ts
new file mode 100644
index 0000000..93fdcf8
--- /dev/null
+++ b/src/items/items.service.ts
@@ -0,0 +1,45 @@
+import { Injectable, NotFoundException } from '@nestjs/common';
+
+export interface Item {
+  id: number;
+  name: string;
+  description: string;
+}
+
+@Injectable()
+export class ItemsService {
+  private readonly store = new Map<number, Item>();
+  private counter = 1;
+
+  findAll(): Item[] {
+    return [...this.store.values()];
+  }
+
+  create(name: string, description = ''): Item {
+    const item: Item = { id: this.counter++, name, description };
+    this.store.set(item.id, item);
+    return item;
+  }
+
+  findOne(id: number): Item {
+    const item = this.store.get(id);
+    if (!item) throw new NotFoundException(`Item ${id} not found`);
+    return item;
+  }
+
+  update(id: number, name?: string, description?: string): Item {
+    const item = this.findOne(id);
+    const updated: Item = {
+      id,
+      name: name ?? item.name,
+      description: description ?? item.description,
+    };
+    this.store.set(id, updated);
+    return updated;
+  }
+
+  remove(id: number): { deleted: number } {
+    this.store.delete(id);
+    return { deleted: id };
+  }
+}