A pattern is something that can be repeated regularly and in a predictable manner.
This concept applies in all contexts—in building, in designing, in IT, and in every context where something needs to be done.
The concept of patterns started late in the 70s in regards to architecture and building designs, but patterns have always been around. Look at nature, for example—it is full of patterns, both repeatable and predictable. They occur in spirals, waves, and broccoli, and in mathematics with symmetric geometry, fractals, and so on.
However, in our context—the IT context—we first found patterns in the middle of the 90s in one of the books I read.
The pattern language continued to evolve to keep up with the speed of the evolution and revolution of IT, and at the beginning of the new millennium, new tools and systems were coming...