# How to Reformat OS X Yosemite on Your Mac 'Complete Guide'

## Introduction

If you're looking for a step-by-step guide on how to format your Mac running OS X Yosemite, you've come to the right place. Formatting can sometimes be necessary due various reasons such as malware infection, system corruption, or simply wanting a fresh start.

In this article, we'll walk through the process of completely erasing and reformatting your Yosemite installation while keeping all essential data safe.

## Prerequisites

Before proceeding with these steps:

1. Backup important files: It's always better to err on the side of caution when dealing with potentially destructive operations.

2. Ensure you're running OS X Yosemite (10.x or later) on your Macbook, iMac, or other supported hardware.

3. Have an external drive or USB flash disk with enough free space available.

## Step 1: Backup Important Data

Before formatting, back up all essential files and data to a safe location such as:

* External hard drives

* Cloud storage services (e.g., Google Drive, Dropbox)

* USB flash disks

* Network shares

### Method A - Using Time Machine

If you have already set up Time Machine backups on your Macbook or iMac running Yosemite:

1. Connect the external drive or backup device to your computer.

2. Go to System Preferences > Time Machine > Select Backup Disk and click 'Backup Now.'

### Method B (Alternative) - Manual Data Transfer via USB

Alternatively, you can transfer important files manually using a USB cable:

1. Connect two Macs with an Ethernet or Thunderbolt 3 cables.

2. On the target Mac: Go to System Preferences > Sharing > File Sharing and select 'Shared Users.'

3. Select your user account from the list on both computers.

## Step 2: Boot into Recovery Mode

To format OS X Yosemite:

1. Power down your Macbook, iMac or other supported device.

2. Press the Command (⌘) + Option/Alt keys while powering it back up until you hear a second startup chime.

3. Release all buttons and allow the computer to boot normally into Recovery Mode.

## Step 3: Erase Yosemite Installation

In Recovery Mode:

1. Connect an external drive or USB flash disk with enough free space (at least equal in size to your current OS X partition).

### Option A - Using Disk Utility

From the recovery menu, select 'Disk Utilities.'

2. Select the target hard drive that contains the Yosemite installation you want to erase.

3. Click on the 'Erase' button and confirm by clicking 'Erase.'

Alternatively:

## Step 4: Reinstall OS X from Recovery Mode or Installers

### Option A - Using Built-in Recovery Menu (Recommended)

1. Connect an Ethernet cable if available for faster internet connectivity.

From the recovery menu, select 'Reinstall Yosemite' then follow on-screen instructions to complete the installation process.

Or:

## Step 5: Reformat OS X via USB Installation Media or Installers

### Option B - Using a Bootable USB Drive (Alternative)

If your Mac doesn't have working internet connection:

1. Download and extract the official OS X Yosemite installer from Apple's website.

2. Use an external drive or USB flash disk to create a bootable installation media using either:

* The built-in 'Create Install Media' option in Recovery Mode

+ third-party tools like Disk Utility, Macrium Reflect etc.

By following these steps carefully and backing up your important files beforehand, you should now have a fresh OS X Yosemite installation on your Macbook or iMac. Remember to always keep an eye out for future updates and security patches to ensure optimal system performance.

If any issues arise during the process or if you're experiencing data loss problems after formatting (e.g., lost documents), feel free to leave a comment below and we'll be happy to help!

Reformatting os x yosemite