Installing Ollama is very simple and supports multiple operating systems:

**macOS Installation:**
```bash
brew install ollama
```

**Linux Installation:**
```bash
curl -fsSL https://ollama.com/install.sh | sh
```

**Windows Installation:**
Download the installer from the official website and run it.

**Common Commands:**

1. **Run a model:**
```bash
ollama run llama2
ollama run mistral
ollama run codellama
```

2. **List installed models:**
```bash
ollama list
```

3. **Download a model:**
```bash
ollama pull llama2
```

4. **Remove a model:**
```bash
ollama rm llama2
```

5. **View model information:**
```bash
ollama show llama2
```

6. **Start API service:**
```bash
ollama serve
```

7. **View logs:**
```bash
ollama logs
```

**API Call Example:**
```bash
curl http://localhost:11434/api/generate -d '{
  "model": "llama2",
  "prompt": "Why is the sky blue?"
}'
```

How to install Ollama and what are the common commands?