diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..204e181
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,19 @@
+# Node.js
+node_modules/
+npm-debug.log
+
+# Environment Dateien (Geheimnisse!)
+.env
+.env.local
+
+# Build-Ausgaben
+dist/
+build/
+.next/
+
+# Betriebssystem
+.DS_Store
+Thumbs.db
+
+# Docker
+docker-data/
diff --git a/backend/prisma/schema.prisma b/backend/prisma/schema.prisma
index df5a29e..fd11250 100644
--- a/backend/prisma/schema.prisma
+++ b/backend/prisma/schema.prisma
@@ -19,6 +19,8 @@ model User {
   followers Follow[] @relation("Following")
 
   createdAt DateTime @default(now())
+
+  notifications Notification[]
 }
 
 
@@ -63,3 +65,14 @@ model Follow {
 
   @@unique([followerId, followingId])
 }
+model Notification {
+  id        Int      @id @default(autoincrement())
+  type      String   // 'FOLLOW' | 'BIRTHDAY'
+  payload   Json
+  read      Boolean  @default(false)
+
+  userId Int
+  user   User @relation(fields: [userId], references: [id], onDelete: Cascade)
+
+  createdAt DateTime @default(now())
+}
diff --git a/backend/src/follows/follows.controller.ts b/backend/src/follows/follows.controller.ts
index 2c86b6e..deb870a 100644
--- a/backend/src/follows/follows.controller.ts
+++ b/backend/src/follows/follows.controller.ts
@@ -1,4 +1,11 @@
-import { Controller, Post, Param, Req } from '@nestjs/common';
+import {
+  Controller,
+  Post,
+  Delete,
+  Param,
+  Req,
+  BadRequestException,
+} from '@nestjs/common';
 import { PrismaService } from '../prisma/prisma.service';
 
 @Controller('follows')
@@ -6,11 +13,59 @@ export class FollowsController {
   constructor(private readonly prisma: PrismaService) {}
 
   @Post(':userId')
-  follow(@Req() req, @Param('userId') userId: string) {
-    return this.prisma.follow.create({
-      data: {
-        followerId: req.user.id,
-        followingId: Number(userId),
+  async follow(@Req() req, @Param('userId') userId: string) {
+    const followerId = req.user.id;
+    const followingId = Number(userId);
+
+    // ❌ Selbst-Follow verhindern
+    if (followerId === followingId) {
+      throw new BadRequestException({
+        error: 'VALIDATION_ERROR',
+        message: 'Du kannst dir nicht selbst folgen.',
+        field: 'userId',
+      });
+    }
+
+    try {
+      // 1️⃣ Follow erstellen
+      const follow = await this.prisma.follow.create({
+        data: {
+          followerId,
+          followingId,
+        },
+      });
+
+      // 2️⃣ Notification für den Gefolgten erzeugen
+      await this.prisma.notification.create({
+        data: {
+          type: 'FOLLOW',
+          userId: followingId,
+          payload: {
+            followerId,
+            followerName: req.user.name,
+          },
+        },
+      });
+
+      return follow;
+    } catch (err) {
+      // ❌ Bereits gefolgt (Unique-Constraint)
+      throw new BadRequestException({
+        error: 'ALREADY_FOLLOWING',
+        message: 'Du folgst diesem Nutzer bereits.',
+        field: 'userId',
+      });
+    }
+  }
+
+  @Delete(':userId')
+  async unfollow(@Req() req, @Param('userId') userId: string) {
+    return this.prisma.follow.delete({
+      where: {
+        followerId_followingId: {
+          followerId: req.user.id,
+          followingId: Number(userId),
+        },
       },
     });
   }
diff --git a/backend/src/notifications/notifications.controller.ts b/backend/src/notifications/notifications.controller.ts
new file mode 100644
index 0000000..5c0cf66
--- /dev/null
+++ b/backend/src/notifications/notifications.controller.ts
@@ -0,0 +1,16 @@
+import { Controller, Get, Req } from '@nestjs/common';
+import { PrismaService } from '../prisma/prisma.service';
+
+@Controller('notifications')
+export class NotificationsController {
+  constructor(private readonly prisma: PrismaService) {}
+
+  @Get()
+  getMyNotifications(@Req() req) {
+    return this.prisma.notification.findMany({
+      where: { userId: req.user.id },
+      orderBy: { createdAt: 'desc' },
+      take: 20,
+    });
+  }
+}
diff --git a/backend/src/pets/pets.service.ts b/backend/src/pets/pets.service.ts
index 3a97928..45d65a3 100644
--- a/backend/src/pets/pets.service.ts
+++ b/backend/src/pets/pets.service.ts
@@ -1,76 +1,119 @@
-import { BadRequestException, NotFoundException } from '@nestjs/common';
+import {
+  Injectable,
+  BadRequestException,
+  NotFoundException,
+} from '@nestjs/common';
+import { PrismaService } from '../prisma/prisma.service';
+import { CreatePetDto } from './dto/create-pet.dto';
+import { UpdatePetDto } from './dto/update-pet.dto';
 
-async createPet(userId: number, dto: CreatePetDto) {
-  // ❌ Beides gleichzeitig verboten
-  if (dto.birthDate && dto.ageYears !== undefined) {
-  throw new BadRequestException({
-    error: 'VALIDATION_ERROR',
-    message: 'Entweder Geburtsdatum ODER Alter angeben.',
-    field: 'birthDate',
-  });
-}
+@Injectable()
+export class PetsService {
+  constructor(private readonly prisma: PrismaService) {}
 
-if (!dto.birthDate && dto.ageYears === undefined) {
-  throw new BadRequestException({
-    error: 'VALIDATION_ERROR',
-    message: 'Geburtsdatum oder Alter muss angegeben werden.',
-    field: 'birthDate',
-  });
-}
+  // -------------------------------
+  // CREATE PET
+  // -------------------------------
+  async createPet(userId: number, dto: CreatePetDto) {
+    // ❌ Beides gleichzeitig verboten
+    if (dto.birthDate && dto.ageYears !== undefined) {
+      throw new BadRequestException({
+        error: 'VALIDATION_ERROR',
+        message: 'Entweder Geburtsdatum ODER Alter angeben, nicht beides.',
+        field: 'birthDate',
+      });
+    }
 
-  // ✅ BirthDate festlegen
-  let birthDate: Date | null = null;
+    // ❌ Nichts angegeben verboten
+    if (!dto.birthDate && dto.ageYears === undefined) {
+      throw new BadRequestException({
+        error: 'VALIDATION_ERROR',
+        message: 'Geburtsdatum oder Alter muss angegeben werden.',
+        field: 'birthDate',
+      });
+    }
 
-  if (dto.birthDate) {
-    birthDate = new Date(dto.birthDate);
-  }
+    // ✅ BirthDate ableiten (Single Source of Truth)
+    let birthDate: Date | null = null;
 
-  if (dto.ageYears !== undefined) {
-    const today = new Date();
-    birthDate = new Date(
-      today.getFullYear() - dto.ageYears,
-      today.getMonth(),
-      today.getDate()
-    );
-  }
+    if (dto.birthDate) {
+      birthDate = new Date(dto.birthDate);
+    }
 
-  return this.prisma.pet.create({
-    data: {
-      name: dto.name,
-      type: dto.type,
-      breed: dto.breed,
-      birthDate,
-      gender: dto.gender,
-      bio: dto.bio,
-      avatarUrl: dto.avatarUrl,
-      visibility: dto.visibility ?? 'public',
-      ownerId: userId,
-    },
-  });
+    if (dto.ageYears !== undefined) {
+      const today = new Date();
+      birthDate = new Date(
+        today.getFullYear() - dto.ageYears,
+        today.getMonth(),
+        today.getDate(),
+      );
+    }
 
-async updatePet(
-  petId: number,
-  userId: number,
-  dto: UpdatePetDto,
-) {
-  const pet = await this.prisma.pet.findUnique({
-    where: { id: petId },
-  });
+    // ❌ Zukunftsdatum verhindern
+    if (birthDate && birthDate > new Date()) {
+      throw new BadRequestException({
+        error: 'VALIDATION_ERROR',
+        message: 'Geburtsdatum darf nicht in der Zukunft liegen.',
+        field: 'birthDate',
+      });
+    }
 
-  if (!pet || pet.ownerId !== userId) {
-    throw new NotFoundException({
-      error: 'NOT_FOUND',
-      message: 'Tier nicht gefunden.',
+    return this.prisma.pet.create({
+      data: {
+        name: dto.name,
+        type: dto.type,
+        breed: dto.breed,
+        birthDate, // ⭐ WICHTIG: berechnetes Datum
+        gender: dto.gender,
+        bio: dto.bio,
+        avatarUrl: dto.avatarUrl,
+        visibility: dto.visibility ?? 'public',
+        ownerId: userId,
+      },
     });
   }
 
-  return this.prisma.pet.update({
-    where: { id: petId },
-    data: {
-      birthDate: dto.birthDate ? new Date(dto.birthDate) : pet.birthDate,
-      bio: dto.bio,
-      avatarUrl: dto.avatarUrl,
-      visibility: dto.visibility,
-    },
-  });
-}
\ No newline at end of file
+  // -------------------------------
+  // UPDATE PET
+  // -------------------------------
+  async updatePet(
+    petId: number,
+    userId: number,
+    dto: UpdatePetDto,
+  ) {
+    const pet = await this.prisma.pet.findUnique({
+      where: { id: petId },
+    });
+
+    if (!pet || pet.ownerId !== userId) {
+      throw new NotFoundException({
+        error: 'NOT_FOUND',
+        message: 'Pet nicht gefunden.',
+      });
+    }
+
+    let birthDate = pet.birthDate;
+
+    if (dto.birthDate) {
+      birthDate = new Date(dto.birthDate);
+
+      if (birthDate > new Date()) {
+        throw new BadRequestException({
+          error: 'VALIDATION_ERROR',
+          message: 'Geburtsdatum darf nicht in der Zukunft liegen.',
+          field: 'birthDate',
+        });
+      }
+    }
+
+    return this.prisma.pet.update({
+      where: { id: petId },
+      data: {
+        birthDate,
+        bio: dto.bio,
+        avatarUrl: dto.avatarUrl,
+        visibility: dto.visibility,
+      },
+    });
+  }
+}