A headless browser allows you to make use of its non-graphic features without the overhead of a graphical user interface. This can be particularly important when it comes to saving time and resources, as rendering even simple web pages can be significant. Headless browser testing is script-driven and easy to automate, making it ideal for high-volume automated testing and streamlining testing processes. It can also catch early functional/performance issues before they affect page design, reducing potential costly redesigns. Additionally, headless browsers have low resource overhead, allowing for small-footprint testing in cloud environments or on minimal physical machines. They don't require reinventing the wheel when it comes to testing, and their scriptability makes them well-suited for automation. However, they may not be suitable for visually testing page rendering or user interaction with the GUI.