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`bridge` is a virtual network that Docker creates on the host to connect containers with each other. It works like an internal router: each container gets its own private IP, and Docker automatically sets up routes and a built-in DNS.

### **How** `bridge` **works:**

- when a container starts, Docker connects it to the `bridge` network and assigns it an IP (for example, `172.17.0.2`);
- containers in this network can reach each other by IP or by container/service name;
- access to the outside world goes through NAT on the host;
- from the outside, the container is unreachable until ports are published.

### **When** `bridge` **is used:**

- for local development;
- for small projects on a single host;
- for scenarios where services need to see each other but stay hidden from the outside network.

### **Example:**

```bash
docker run -d --name app nginx
docker run -d --name db mysql
```

Both containers end up in the `bridge` network and can communicate, for example: `mysql://db:3306`.

### **Key features of** `bridge`**:**

| Property | Description |
|---|---|
| Isolated from the host | Containers are in their own private network |
| Has DNS | Containers see each other by name |
| NAT outward | Containers have internet access |
| Ports required for inbound access | `-p 8080:80` |

**Summary:** `bridge` is a local private Docker network for containers on a single host to interact, isolated from the outside network with a convenient internal DNS.

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