How Does a Computer Count?

As an initial step, engineers agreed to represent the binary digit $\bf 0$ using a low electric current, and the digit $\bf 1$ using a high electric current.

• In other words, if a low electric current flows through the computer, it means we received the digit $0$, and, on the other hand, if a high electric current flows through the computer, it means we got the digit $1$.
• This is why the counting system of computers is built up of $0$s and $1$s: computers can only understand these two symbols.

Once this decision has been made, you can apply multiple currents in a row to represent a bunch of $0$s and $1$s, which, as we will see, could then represent numbers in other bases (e.g., base $10$ and base $16$,) letters, symbols, strings, objects like images, videos, and any other data structure that you can imagine (and implement.)

Now that we understood why the computer uses a binary counting system, let's define a few frequently-used computer science terms that we'll use throughout this course.