ImageJ is an open-source image processing and analysis software developed by the National Institutes of Health (NIH). Designed for scientific and medical research, it enables users to conduct a wide range of image analysis tasks, such as measuring, annotating, and modifying images. ImageJ supports a variety of image formats and offers extensibility through plugins and macros, allowing users to customize and enhance its functionalities to suit specific needs. Its community-driven development model ensures a robust and versatile tool for both novice and expert users.