Note: This method was tested on a device running Android 2.2 Froyo.
Most Android phones either come with an SD card or give you the option to install one. Expanding your device’s storage space in this manner can be a great way to store more music, photos and other media, while simultaneously preserving your device’s internal memory for applications and user data.
Before you can start utilizing a new SD card, it will need to be formatted. Fortunately, Android has this capability built-in and it is a relatively painless process to accomplish.
First, if not already there, go to your home screen by pressing the Home button on your device.
Then, select the Menu button and press Settings.
Scroll down the list until you find the SD & phone storage entry and select it. The following screen will give you a summary of multiple aspects of your card, e.g., its maximum capacity, how much space is available, etc. In order to proceed, you will now be required to unmount the SD card by selecting the Unmount SD card option in the menu.
Caveat: Before you proceed, remember that formatting a card will make all data currently stored on the card inaccessible, barring the use of data recovery tools/methods unbeknownst to many end users.
If the card is successfully unmounted, the Format SD card option will become available. Select it to initiate the process, and after a few moments, you will be ready to start copying media to your new storage space.
Source Online Tech Tips
Image via thomcochrane