It doesn't take much to reach or even exceed the storage capacity on your desktop or laptop. Just using your computer every day, adding files, new software or graphics will affect storage. Audio and video files, given their size and complexity, will get you to your max sooner than will a photo album, word document or excel file. An external hard drive is a great solution to add storage. It's portable, easy to use and cost effective. While this isn't as simple as shopping around online and grabbing the first drive that looks cool or makes extravagant promises about storage and capacity, you'll need to do your research, ask friends and family for ideas and read various customer reviews. 

Capacity: How Much Is Enough?

The first thing to look for when purchasing an external hard drive is capacity. That's the term for how much space is on the drive, a value often expressed in gigabytes or terabytes. Here's a brief explanation of what these sizes represent. 

A single gigabyte is 1 billion bytes, which CNET reports is enough room to store about 500 pictures taken with a smartphone. You can store approximately 200 songs in the same space. 

One terabyte is 1,000 gigabytes, or 500,000 badly focused pictures of your thumb. According to PCMag.com, you could store enough music in a single terabyte to play 750,000 MP3s. For most people, a medium-sized unit is more than enough. Do some research on the various types of hard drives available on the market, sizes, cost and durability. 

Think About Performance 

Like capacity, performance is another technical-sounding metric that may not make sense intuitively to the average consumer.  For an external hard drive, the performance is really about the speed with which it accomplishes tasks such as data retrieval and transfer. This varies with the type of drive and connection port you're using, but an easy way to think about it is to imagine you're transferring data from your CDs to the external hard drive and how long it takes to move the contents of the entire CD into storage? Again, like with all technology advances, speeds and performance get better and faster all the time. 

A Cost/Benefit Analysis

As with any purchase, you probably want to do a cost/benefit analysis to determine the best hard drive for your budget and one that meets your current and anticipated future needs. There is a price quality relationship, so do your research before you invest in hard drive.

There are different types of external hard drives, including desktop hard drives and notebook hard drives, (also known as portable hard drives). A desktop hard drive is designed for desktop computers and a portable hard drive is much smaller and lighter. Portable hard drives are popular with those who are mobile and need portable storage. With a portable hard drive, you can easily pick up and travel virtually anywhere with large amounts of data. Use an external hard drive to free up space on your internal hard drive and optimize performance.

Desktop-style drives have a disk inside that physically spins to handle data, just like the internal hard drive you're already using. This type of drive usually isn't portable, and it might come with its own fan to keep it cool. Desktop-style drives can run fast, and they generally have the largest capacity.

The other type of hard drive is the notebook-style, or SSD type. These use solid-state electronics. SSDs are attractive to some buyers mainly because they're portable and less likely to overheat or fail when they're dropped.  In general, expect to pay about twice as much per unit of storage for an SSD as you might for a desktop unit.

Adding an external hard drive to your computer takes patience and care to be sure you're getting the best package for the money. If you're mostly working from the office, or if you need huge capacity and high speed, look for a desktop-style drive. If you're working from a remote location, or if you need to share data with others, find an SSD that fits your budget and needs. 

Cited Resources:
http://www.cnet.com/topics/storage/buying-guide/
http://www.pcmag.com/article2/0,2817,2358135,00.asp