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Just Because You Are
Paranoid Doesn't Mean They
Aren't Really Out to Get You!
 When it comes to computers (and even cell
phones) a little paranoia can be healthy.
As
we've noted, in order to communicate with the network computers must send as
well as receive signals. These signals that can be picked up by savvy
computer users in the area -- even someone parked in a car on an adjacent
street.
Never enter personal information such as credit card information or
your address on a public computer or even when using your own laptop in a public
area with a shared wireless connection.
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As a convenience to users, browsers can even save personal
information such as sign-on names and passwords (if this feature is turned on),
which will then be available to subsequent users of the computer.
Passwords
When it
comes to protected Internet accounts, one of the biggest pains is maintaining
passwords.
Passwords can be relatively easy for the wrong people to figure out --
especially if they know something about you: your dog's name, where you were
born, etc., etc.
There are even programs that will run through lists of common passwords and try
to use them to get into your e-mail (as some well-known people have
unfortunately found out) or to sign on to your bill pay or banking records.
Many of these secured services will lock out attempted uses of the wrong
password -- and that user may be you, if you can't remember which password you
used.
Although there are programs that remember all your passwords for you,
the risk, of course, is in the wrong person could get access to that program.
Since
passwords should be periodically changed -- some services force you to regularly
change them -- some people use a system that incorporates the number of the
month, such as "Mar09garet."
If the system recognizes upper and lower case letters, there's added protection
in using some combination: "maRgaRet."
For another level of security some systems require numbers to be a part of the
password: "54margaret."
"Margaret," by itself, would not be a good password. In addition to it
being a common name -- maybe even the name of the user -- any word in a common dictionary is in the "vocabulary" of password cracking
software.
What you don't want to
do is write the password down on a post-it and stick it to the computer monitor
(it's been done in companies!) or even somewhere under your desk (people
know this is a good place to look).
When You Delete Data It's Still There
Although you are much safer at home with a secure Internet
hookup, as you undoubtedly know from watching detective shows, your computer
hard drive keeps a fairly good record of the recent sites you've visited, the
pictures you've looked at, and even the files you think you've erased.
"Deleting" a file as it's normally done does not really erase it
-- it only deletes the index entry that points to the original file. Assuming the data has also been erased is a little like pulling the index card from a card catalog
in the library and assuming the book it points to is also gone!
Likewise, with your computer the data is still there (for those
who know how to find it) until that space if overwritten with new data.
There are programs available that will restore "deleted"
files. These are handy to have if you accidently delete a file you need. Of course,
the quicker you "undelete" a file the greater the chance of completely restoring
it before it's overwritten by something else.
Government computers and corporations with
trade secrets use computer deletion programs that not only delete the index
entry, but overwrite the original data space at least two times with randomly
generated data (gibberish).
To speed things up, browsers
(like the one you are using to read this) generally retain
certain data on the hard disk - where it's much faster to load than downloading
it from the Internet. This "data" includes photos. Most browsers have an option
within "tools" options to clear personal data and browsing history --
sometimes automatically each time you close the browser.
"Smartphones"
The major cell phone companies provide high-speed internet for
both "smart phones" and laptop computers. In the latter case this capability is built
into the computer or makes use of a device attached to the laptop through a USB
port connection.
Although this approach -- typically called a 3G or 4G wireless
connection -- is much faster than the standard telephone service, it's not as
fast as today's better high-speed home Internet connections. The advantage is that you
can "get on-line" most anywhere.
Today's cell phones are actually miniature
(and in many cases rather sophisticated) computers. Some even have hard drives.
Much of what we've said about computers also applies to cell phones.
The features of cell phones like the iPhone probably don't need
to be enumerated to young readers who routinely use them to listen to music, send text messages, and send and receive pictures. Most with built-in
cameras can make short movies.
Hyperlinks
and
Error Correction
When you click on a computer hyperlink you may be taken to a computer site thousands of miles away. This means that the signal may have to be routed through hundreds of relay points.
If it weren't for error correction, momentary interference or interruptions could easy scramble the message. To stop this from happening data is sent and received in blocks of information. Before a block is sent it's mathematically analyzed and a checksum (a calculated value reflecting the nature of the original data) is transmitted along with the data block.
If the checksum on the receiving end doesn't match the checksum of the original data block, an error signal is transmitted to the originating source
and that data block is immediately sent again. You might assume that the blocks of data are all sent over the Internet using the shortest route between computers. That's not necessarily the case. In fact, depending in Internet conditions, the blocks of data within a single message can take very different geographic routes getting to their destination.
This is actually one of the strengths of the Internet. If problems develop at one or more relay points, traffic is automatically rerouted. As we will see in the next module, this feature was a cornerstone in the original Internet design. Each block of data that is sent over the Internet carries an "address." (There will be more on this in Internet Module 4.) Once the individual data blocks arrive at their destination, they are combined in the intended sequence.
This process can be likened to using dozens of post cards to send a term paper from one person to another with each post card containing only contain one or two sentences. Let's assume you address each post card to the same person and then drop them all in a mailbox. From there they could go different routes; some might go by trucks and some by aircraft. Once they arrive at the common destination, they have to be put in the proper sequence. This analogy shows you a bit of the complexity
of how data is sent over the Internet.
The Worldwide Wait?
 The Worldwide Web is sometimes referred to as the "worldwide wait," because the Internet sometimes slows down to a crawl, or even freezes, during high use periods.
It doesn't help that the United States is behind many other
countries in Internet speed. If the Internet had been designed from the beginning to accommodate millions of simultaneous users, these problems might have been avoided. However, the original design didn't envision a fraction of the traffic we now see. Ever since the Internet "took off," equipment and facilities have been trying to play "catch up" -- and never quite catching up.
More information on some of these topics can be found in the Resources file.
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such as a USB jump drive (shown on the left), a recordable
CD or a external hard drive
telephone lines. 
Then, something called GUI (graphical user interface, pronounced goo-ey) was devised. This made it possible to display interactive images on computer screens.
