A great feature of the Droid (and most other Android phones) is the included expansion-card slot, which allows you an infinite amount of expansion beyond what's available internally for app storage. Expansion cards have unlimited uses and capacity, and you can add as many cards as you need. The expansion-card slot is a key feature that's not available in the iPhone.
The expansion-card slot on the Droid accepts Micro SDHC (Micro Secure Digital High Capacity) cards, which are even smaller than the SD cards used in many digital cameras. Micro SDHC (which the industry has shortened to microSD) memory cards are just a hair over half an inch on their longest side and are easy to lose, so keep them in a safe place.
The microSD card slot on the Droid is typically located on the bottom of the phone in the battery compartment (Figure 4.7). To access it, you sometimes have to remove the battery first—which shuts down the phone. Plan ahead: First shut the Droid down gracefully by pressing and holding the Power key and then touching Power Off.
Figure 4.7 The Droid X with its battery and Micro SD card removed.
Droids support microSD cards up to 32 GB, but the 16 GB card that comes preinstalled should be more than adequate for most users. If you need additional storage, you can purchase more 16 GB cards for around $20 each; 32 GB cards sell for around $65 each.
Due to Moore's Law (which I define in the following note) and the dynamics of book publishing, there's a good chance that 64 GB or even 128 GB microSD cards could be available by the time you read this book. Before you buy such a card, make sure that the Android operating system (OS) you're running supports the larger card. A 32 GB card is a waste if your phone recognizes only 16 GB of it.
When a card is installed in the Droid, you can unmount it, format it, and view its available storage by touching Settings > SD Card & Phone Storage (Figure 4.8).
Figure 4.8 The SD Card & Phone Storage Settings screen.