💡 Simple Definition:

A Monolithic Architecture is a single, unified codebase where all modules of an application (frontend, backend, business logic, database access, etc.) are tightly coupled and deployed together as one unit.

“Mono” = single, “Lithic” = stone → means one solid piece of software.

🧠 Imagine This:

You’re building “Devsync Learn” — your edtech platform.

In a monolithic setup, your application might look like this:

Devsync App (Single Codebase)
│
├── auth/
│   ├── login.ts
│   ├── signup.ts
│
├── courses/
│   ├── createCourse.ts
│   ├── getCourses.ts
│
├── users/
│   ├── profile.ts
│   ├── updateProfile.ts
│
├── payment/
│   ├── initiatePayment.ts
│   ├── verifyPayment.ts
│
├── database/
│   ├── prisma.ts
│
└── server.ts  <-- main entry point (express.ts or fastify.ts)

All of this runs as one Node.js process, deployed as one Docker image / server / build.

If you make any change (even a typo fix), you have to rebuild and redeploy the entire application.

🏗️ Architecture Diagram:

                ┌───────────────────────────┐
                │       Monolithic App      │
                │---------------------------│
                │  Auth Module              │
                │  User Module              │
                │  Courses Module           │
                │  Payment Module           │
                │  Notifications Module     │
                │---------------------------│
                │ Database Access Layer     │
                │ (ORM / Prisma / Sequelize)│
                │---------------------------│
                │  Web Server (Express.js)  │
                └───────────────────────────┘
                           │
                           ▼
                ┌───────────────────────────┐
                │       Database (SQL)      │
                └───────────────────────────┘

Everything — user auth, payments, courses, notifications — lives inside one giant application binary/process.

⚙️ How Does It Work?

1. The user sends a request:

   → e.g. POST /api/login

2. The monolithic app receives it (via Express/Fastify).

   → It routes internally to auth/login.ts.

3. That function executes business logic (validate user, generate JWT, etc.)

   → Calls database via Prisma/Mongoose.

4. The same process handles other endpoints too (courses, payments, etc.)

   → All share the same memory space, same runtime, and same database connection pool.