A CD-ROM is a plastic disc with a thin aluminium layer from which music, texts, and other data can be retrieved. Like everything else in the world of computers, these files are also stored in the numeric sequence of 1 and 0. In this case, there are tiny grooves for 1 or none for 0. A laser beam in the reader scans these grooves, which reflect the laser beam in different ways. From these laser reflections, the chip in the computer or in the CD player deciphers the data present on the CD, which could be music, text, photos, or complete programs.
In 1994, a climbing robot by the name of Dante II was sent for the first time to explore the interior of a volcanic crater in Alaska. After entry into the crater, the measuring devices and cameras, hidden in the legs of the robot, started exploring the dangerous terrain. By analyzing the data and the images received from the surroundings, an onboard computer calculated each step of the robot. It was able to overcome boulders as high as 1 m and descended 70 m deep in the volcano before crashing. Fortunately, it had sent all the data collected and the images to the research station via satellite before it crashed.
Many people transmit malicious viruses, mostly through e-mails. The virus is a small hidden program that deletes the data or destroys parts of the operating system, which controls the computer. The viruses then automatically go to other computers through e-mail addresses stored in our computer. Some protection is offered by the antivirus programs. The safest way to stop viruses entering your computer is not to open attachments from unknown senders, especially the ones with an unusual ‘subject’.
For reading on-screen texts the blind need a special reading line in Braille script. For this, the computer converts the text in electrical signals, which are then pressed upwards by the corresponding points in the reading line. The blind can then feel the Braille. Or the text can be read aloud to them by a special speech program – they can also dictate texts in the same way. In this way, the visually challenged can also surf on the Internet. Pictures must always be accompanied by text; otherwise the blind cannot ‘read’ them.
In 1969, some American universities and research institutes needed more computing power, and connected their computers with one another. Later, more and more computers got connected, giving rise to a worldwide network called the Internet. On the other hand, the ‘WWW’ – and the sending of e-mails – is a service, which is offered within the Internet. It is a worldwide association of information pages connected with one another called the ‘World Wide Web’. The basic requirement for searching in the WWW or for sending e-mails is access to the Internet, maybe through a telephone line. Surfing, i.e., searching for information, in the WWW is not possible without a special program called a browser which understands the language of the Web. The address of the website we want to look at is typed in the browser. For instance, the website [custom_search_and_filter]