Image segmentation is the most important part in digital image processing. In image segmentation, digital image is divided into multiple set of pixels. With the growing research on image segmentation, it has become important to categorise the research outcomes and provide readers with an overview of the existing segmentation techniques in each category. Image segmentation is generally required to cut out region of interest (ROI) from an image. Currently there are many different algorithms available for image segmentation The state of art research on each category is provided with emphasis on developed technologies and image properties used by them. In this article, Categories and Methods of Image Segmentation is briefly explain with suitable practical application.