Microsoft Office Tutorials and References
In Depth Information
A newer, more expensive DVD format is Blu-ray, which is a higher capacity and better quality
than standard DVDs, especially for high-definition audio and video. A Blu-ray Disc (BD) has
storage capacities of 100 GB, with expectations of exceeding 200 GB in the future.
Many types of recordable and rewritable DVD formats are available. DVD-R, DVD+R, and
BD-R allow users to write on the disc once and read (play) it many times. DVD-RW, DVD+RW,
and DVD+RAM are three competing
rewritable DVD formats. Similarly, BD-RE
is a high-capacity rewritable Blu-ray format.
To write on these discs, you must have a
compatible drive or recorder.
For more information, visit
then click DVDs.
Cloud storage is an Internet service that
provides hard disk storage to computer
users (Figure 29). Fee arrangements vary.
For example, one cloud storage service
provides 25 GB of storage free to regis-
tered users; another charges $5 per month
for 150 GB of storage. For organizations,
cloud storage services typically charge for
storage on a per gigabyte basis, such as
15 cents per gigabyte.
Types of services offered by cloud stor-
age providers vary. Figure 30 identifies a
variety of cloud storage providers.
An example of one Web site advertising its storage service.
Cloud Storage Providers
Web Site Names
Type of Storage Provided
Box.net, IDrive, Windows Live SkyDrive
Backup or additional storage for any type of file
Digital photos, digital videos, messages, and personal information
Documents, spreadsheets, presentations
Gmail, Windows Live Hotmail, Yahoo! Mail
Amazon EC2, Amazon S3, Nirvanix
Some of the more widely used cloud storage providers.
A communications device is a hardware component that enables a computer to send (transmit)
and receive data, instructions, and information to and from one or more computers or mobile
devices. A widely used communications device is a modem (Figure 1 on page COM 2).
Communications occur over transmission media such as cables, telephone lines, cellular radio
networks, and satellites. Some transmission media, such as satellites and cellular radio networks,
are wireless , which means they have no physical lines or wires. People around the world use computers
and communications devices to communicate with each other using one or more transmission media.