What is a software or logic system, and what makes a system modern? Software is a generic term given to the programs that make a computer do work. Software is "soft" because it can be changed and replaced on a computer without any physical parts being affected.
Some software is simple, consisting of a single file or script of a few lines. Other software is complex, consisting of tens, hundreds, or even thousands of separate programs and data storage elements, all working together to solve a set of problems. Both of these are "systems" of software components and data, or Sofware Systems.
The web browser you are using to read this page in is a software system for displaying web content to people. Software systems might be very small, such as a simple text game on your phone. They can also be very large, such as the systems that process income taxes, or track airline flights.
When developers plan a new software system, they usually select the technology that they determine to be the best fit for solving that problem at that time, given the amount of time, money, and expertise they have to build the system. But software technology is constantly evolving, and the best option today is guaranteed to become obsolete in some future tomorrow. For a large system, that can occur before the system is ever completed. Technology will change for all kinds of reasons, but whatever the reason, software developers have to constantly evalate the current state-of-the-art and pick the right points to update the software systems they support.
This site is about understanding software system technology and what makes a system Modern, so we can understand when to introduce change.