Binary is a numerical system that is unique to others. Although it is not used it is still interesting to know. In binary only two digits are used; 1 and 0. The sequence goes like this: 0, 1 10 11 100 101 110 111 1000 etcetera etcetera. This is quite similar to the standard system of numbers. Here's why:
In the decimal (the normal number sequence) system the digits are 0-9. When nine is reached the nine is reduced to zero and the number on the left is one. This works because you have 01, 02, 03, 04, 05, 06, 07, 08, 09, and then 10. When 99 is reached the 09 is reduced to zero and one is added to the 90. This is reset to zero and adds one to the left. Which makes it one-hundred. How is this similar to binary? Well replace the 9 with one. Now you have 00 01 10 11. Binary isn't as confusing as it appears. Thinking about it this way we can continue the sequence from 1000. 1001 1010 1011 1100 1101 1110 1111. Adding in binary is easier than the decimal system (10 + 1 = 11 1100 + 11 = 1111) But multiplacation is a major pain. Eg.1100 x 10= ?. Obviously 12 x 2 is 24 but writing in binary is hard to work out.

Here is some intersting facts about binary:

Binary is the only other numerical system to only use numbers.

Binary is used in computers.

Binary was used as a code for millitary intelligence

There is a sequence to what the max number of ones and value in the decimal system is. Basically the amount you add increases by one and starts of as 2. This is highly similar to the square number pattern where the amount added starts off as three and increases by two.

Base counting is another way to describe this. When you are base counting an x amount of numbers are used. The highest being ten and the lowest being two. For now we will refer to base 5. In base 5 five numbers are used. 0-4. When 1 is added to four it gets reset to zero and one is added to the digit to the left. Eg. 31 32 33 34 40 41 42 43 44 100. This applies to binary which in other words is counting in base 2.
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