Yes, the waterfall software development methodology is still in use and has not been phased out. It has been in use for more than 20 years now and is basically about planning the features of the software application upfront before the development starts. The waterfall model is based on a predictable timeline and moves step-by-step. When you know all the project requirements from the start, it becomes easier to manage the project using the waterfall model. It is still preferred when clients are keen on predictable, structured management instead of highly iterative software development practice. It gives a clearer picture of the phase of the project and allows better communication with stakeholders.