A wireframe is simply a diagram of a GUI. It's a visual guide to how a GUI will look, without all of the detail such as images and rendering. Think of it a blueprint to an architect, or as like a wiring schematic to an electrical engineer.
From an end-user perspective, there are very palpable ways of interacting with modern software. This could be through a traditional desktop computer or increasingly, through touchscreen mobile devices. It can even be through virtual and augmented reality, complete with voice commands and haptic feedback.
The commonality between these devices and interactions is that they all have a crucial visual element that is an integral part of the user experience. In other words, very few pieces of software don't have a GUI! So, when you are designing software, the GUI element is something you need to take...
