# macOS Sierra / Mojave

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Mac : Factory reset / Fresh install ( macOS Sierra , Mojave )
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### Before You Start

* Back up your data using Time Machine (recommended)
* Ensure stable internet connection
* Have your Apple ID and password ready (optional)
* Set aside 3-5 hours for the complete process

### Step 1: Enter Recovery Mode

1. Turn off your Mac
2. Press the power button
3. Immediately press and hold `Command (⌘) + R`
4. Keep holding until you see the Recovery screen (about 5 minutes)
5. Connect to Wi-Fi when prompted
6. Enter your Wi-Fi password

### Step 2: Erase Your Drive

1. Select "**Disk Utility**"
2. From the sidebar, select "**Macintosh HD**" (internal drive)
3. Click "**Erase**" at the top
4. Keep default settings in the format options
5. Click "**Erase**"
6. Wait for the process to complete
7. Verify the free space is available
8. Exit Disk Utility

### Step 3: Reinstall macOS

1. Select "**Reinstall macOS**"
2. Click "**Continue**"
3. Read and agree to Apple's terms
4. Select "Macintosh HD" as installation destination
5. Click "**Install**"
6. Wait for installation (up to 5 hours)

### Step 4: Initial Setup

1. Select region and language
2. Connect to Wi-Fi
3. Migration Assistant options:
   * Restore from Time Machine backup
   * Select "Don't transfer now" for fresh install

### Step 5: Account Setup (Optional)

1. Apple ID setup:
   * Enter your Apple ID and password
   * Skip if selling/giving away the computer
2. iCloud options:
   * Keychain (can be disabled)
   * iCloud Desktop & Documents
3. Additional features:
   * Siri setup
   * Analytics sharing preferences

### Important Notes

> ⚠️ **Warning**: This process erases all data. Back up important files before starting.

* Default formatting options are recommended
* Installation time varies by internet speed
* Computer will restart several times

### Alternative Installation Method

* You can also install using a flash drive (bootable installer)
* Useful for offline installation
* Requires separate preparation steps

### After Reset

1. Verify successful installation
2. Configure system preferences
3. Install necessary applications
4. Restore data if needed

### Troubleshooting

* If Recovery Mode fails:
  * Restart and try again
  * Ensure Command + R is pressed immediately after startup
* If installation is slow:
  * Check internet connection
  * Connect to faster network if possible

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*Note: This guide works for both macOS Sierra and Mojave. Some interface elements may vary slightly between versions.*