FAQ

A bit is the smallest representation of a number within a computer. It has two possible settings on or off or zero or one. It is by combining together bits that larger and larger numbers can be represented. A bit represents a number by a power of 2. For instance we represent a number by a power of 10. Example: one bit can represent either zero or one. Two bits together can represent zero, one, two, or three. Three bits can represent numbers from zero to seven. To figure out how large a number can be represented by the bits, take the number of bits and compute them as a power of 2 and then subtract one for the representation of zero. Let's go back to our example of 3 bits. That would be 2 x 2 x 2 - 1. Two times two is 4 times two again would be eight, then minus one would be seven. Hence, three bits can represent the numbers zero thru seven. Within the computer each bit in a sequence represents some value. For instance the first bit always represent 1 and depending on whether that bit is on or off tells whether or not it is a 1. the next bit represents 2. Why? Simple 2 to the power of zero is always 1. 2 to the power of 1 is always 2. In our little example of 3 bits. The first bit represents 1, the second bit represents 2 and the third bit represents 4. Notice how it progresses? Also notice how the third bit is the first part of our computation? (2 x 2 = 4) So if you wanted to represent 8, you would need another bit which coincidentally would represent 8. But now because we have 4 bits the largest number we can represent is now 15. To figure it another way, it would be 1 + 2 + 4 + 8 = 15.

A byte is simply 8 bits put together in a logical format that's used everywhere in computers. Using the power of 2 from What is a bit? you find that a byte can represent the number zero through 255.

A nibble is 4 bits or half a byte, hence the name nibble. Why a nibble? Because an easy way to represent a byte is by using hexadecimal. Where in decimal we have the numbers zero thru 9, in hexadecimal we have the numbers zero thru 15. From 10 to 15 the numbers are represented by the letters A thru F. So if you ever see something like "2F" it's probably a hexadecimal representation of a byte. Which consists of two nibbles.

Kilo means thousand. So the rough translation is one thousand bytes. But in computers it's never that simple. A K is actually 1,024. Why? See What is a bit? 1,024 is 2 to the tenth power. Which is why it is 1,024 not one thousand for a K byte.

Mega means million. So it should mean one million bytes. But just like with a kilobyte it's not that straightforward. A mega-byte is actually 1,024 x 1,024 or 1,048,576. Also you can think of it as 2 to the 20th power.

Giga means billion. Like with kilobyte and mega-byte one would think that it would simply mean 1 billion bytes, but alas, it doesn't. A giga-byte is actually 1,073,741,824 or 1,024 x 1,024 x 1,024. Also you can think of it as 2 to the 30th power.

Tera mean trillion. If you've been reading this through from the beginning, by now you know that it's not going to be as simple as 1 trillion bytes. It is going to be: 1,099,511,627,776 bytes or 1,024 x 1,024 x 1,024 x 1,024 or 2 to the 40th power.

Central Processing Unit (CPU). The real brains of the computer.

Random Access Memory or RAM. RAM is the memory inside your computer. Most computers now have gigabytes of memory. It is called random access because the CPU can access any part of the memory connected to it. It is also called "volatile" because once the power goes off, whatever is stored in the memory is lost.

Read Only Memory or ROM. Read Only memory is memory that the CPU can read but can't write to. Hence why it's called "read only." A lot of times ROM is used for things like "firmware." Firmware is small pieces of code that tells the CPU what to do with a device including it's own motherboard.

Like the biological version, a computer virus, or "virus" is a small program which attaches to other software on a computer. Often times once it begins running it will make copies of it's self by grabbing the contacts on that computer and sending out copies of it's self to everyone in the contacts. Sometimes, that is all they do. Other times they lay dormant until a specific event such as a date or perhaps a signal coming in. Once it becomes active it may do anything from drawing things on the screen to wiping out all the files on that computer.

Anti-virus is software designed to detect viruses and eliminate them. Antivirus programs have several different ways of detecting viruses. Most programs have a database of patterns of viruses. Like a biological virus has DNA, it is possible to identify a virus by checking it's DNA. In the same way, the pattern is part of the code in the virus that always shows up when a virus has infected a computer. Other antivirus programs connect into elements of the operating system and then watches for suspicious activity such as writing to certain files, connecting to the network and other things. Often times these are not as successful because the viruses can disconnect the antivirus program from the operating system, effectively blinding the antivirus program.

Spyware comes in many forms. Some just simply tracks certain websites you go to, or just simply track where you're going on the net. Others log your keystrokes. Depending on how it's set up they will either at certain times transmit back to who ever set them up. Others dump everything when they get a specific signal. They can be very innocuous such as tracking websites, to very dangerous such as key logging. When your keystrokes are logged, you could be typing in your password or you could be typing in your credit card number.

A router is for networks. What you know as the internet is a network protocol called "TCP/IP." Everything is based on packets. For instance when you go to a website, your computer sends a packet to the web server (the website) asking it to connect to it and to send back packets that contains the home page of the website. A router manages sending the packets to the appropriate machine.

A firewall is a wall intended to prevent a fire from spreading to another compartment, room or building. The typical car has a firewall between the passenger compartment and the engine. It is simply a thick metal wall that helps to prevent a possible engine fire from burning up the passengers. Likewise a computer firewall is intended to prevent a fire from spreading. Only a fire in this case would be hackers. On a personal computer most firewalls consist of monitoring the applications on the computer. When an application attempts to connect to the internet, the firewall will stop the application and notify the user that this application is trying to connect to the internet, do they want to allow it? If the user says yes, it will let the application continue. If not, the application is denied. This is very important. If a computer is infected with a virus, or if someone hacks into it, the application will change. When it changes, the firewall recognizes this change and when the application attempts to connect to the network again, it will again stop it and ask the user if it is OK. The user must pay attention to these messages. If they haven't upgraded the application and the firewall is asking if it's OK to let it connect, it's time to say No and investigate that application. Or if the user opens an application that normally doesn't access the internet and now all of a sudden the firewall is saying it wants to access the internet, it's time to stop that program and at the very least, uninstall and reinstall that application.