Non-customised settings: usually, when installing a program or signing up to a service the company will make assumptions about how you would like things to work, based on what the majority of their users choose to do.
Every time you use your computer the data is stored on your hard drive is random places, meaning that it can become 'fragmented'. Defragmenting your computer 'filters' everything, putting all these bits of data back into one section so that your computer can run much more effectively.
Digital rights management: a way of controlling how different types of files are used eg, music tracks bought via one company's software/music player might not be playable by other types of software/devices.
Can stand for either 'Digital Video Disc' or 'Digital Versatile Disc': a storage format much like a CD, but with the ability to hold nearly seven times as much information. Mainly used for video files, but can be used for most types of file.