Many people will argue that there's always a need for more capacity, and cellular networks are certainly a prime example of that. Because every time an improvement is made and we can fit more people into the same network. Using a more sophisticated technology, that capacity quickly gets eaten up. So we were having this problem in this time period, with amps, in around the 1990s. Where the network was then once again bursting at the seams. So there were many, many millions of mobile subscribers by this time, and we needed to find a way to do more with what we currently had. And make spectrum sharing more efficient. So engineers began experimenting with a fundamentally different type of signal. And what do we really mean by that? Well if we look at the way that signals were going through networks at this time. They were all traversing networks in their exact electrical forms, which we call an analog signal. A good analogy to analog signal is just speech, which is really what we're transmitting here, we're transmitting a speech wave form. So it goes up when you speak higher with more intensity, and goes down when you speak lower, higher, lower, and so on. You can view this as a speech waveform. And so from the time that it was sent from your phone to the time that it got to the receiver it would look exactly like this anywhere in the network. With the rise of computers, engineers realized that they can more efficiently deal with these signals if they use a different type of signal. So, rather than having it traverse in this analog form, they said, let's first convert it to a bunch of ones and zeroes, which is really computer code. And each of these ones and zeroes are called bits, and a bit is, just as we said, a 0 or a 1. It's just on, off type of computer logic. And so, this is called a digital signal. This is a type of digital signal, and digital signals are completely discreet, in both time and value. So, it can only take the value of either a 1 or a 0. So this would take the value of a 1, then 1, this takes a value of 0, this takes a value of 1. And so on whereas the analog signal has many values that it takes in between infinite number of values that it takes when it's rising up to the top here. And coming back down, and then rising back up, going back down, and so on. So, while we hear analog signals like speech waveform. When it comes back out it's shot out as an analog signal. Computers can only hear and process, digital signals. So computers don't like to hear analog signals. They only like to hear digital signals. So as we started to use computers in networks, we started to use digital technology and that gave enormous capacity advantages as well. So the transition from analog to digital, really marked the migration from 1G to 2G. When we started to have digital phones, and phones that had computers in them and so on, we started to get more features than just the standard call. So in 1990 a Motorola phone looked something like this, still only used for calling. So you could dial someone's number, and then you can call them and hear them on the other end and speak. By 2000 a phone looked more like this, so you'd actually have a digital readout screen. Which is was a [UNKNOWN] digital technology as well as features like texting. So once we hit 2G that's when they started to see people being able to text.