Whether you're replacing an old hard drive in your desktop, looking for extra storage capacity in a laptop hard drive, or wanting a reliable backup hard drive, finding the best solution can be either simple or complicated, depending on your needs. Two fundamental factors for you to consider are capacity and speed.
Capacity is the amount of space you need for your files, determined by both quantity and quality, because better quality results in larger files. To illustrate using an MP3 music file example: A 16GB HDD will hold around 4,000 songs (4 minutes long/128 kbps bit rate), while a 1TB HDD will hold around 250,000 of the same size songs. (1TB/terabyte is equal to 1024GB/gigabytes.) Another example: If you’re a photographer and you store large, raw photographs on your computer before using photo editing software to enhance and manipulate the images, you'll need more capacity than if you primarily use your computer for typical business applications. So, bottom line, estimating whether your capacity requirements can be satisfied by a 1TB hard drive, a 2TB hard drive, all the way up to 16TB hard drive or larger, is essential to choosing the best hard drive for you.
Speed determinations are a little less cut and dried, because the internal speed of the computer hard drive itself works with the speed of the connection between the HDD and your computer to influence your load/save/transfer speeds. Speed is especially important if you enjoy playing PC games, where slow load times, stuttering and excessive lag can mean the difference between advancing and winning — and not.