D-90 is a term often used in various contexts, including military operations and project management, to indicate a timeline or countdown to a significant event or deadline. The "D" typically stands for "Day," and the number represents the number of days remaining until that event occurs. For example, D-90 would mean there are 90 days left until the specified date. In military contexts, D-90 might refer to the preparation phase before a planned operation, allowing teams to organize resources and strategies. In project management, it can signify a critical milestone, helping teams track progress and ensure timely completion of tasks related to the project, such as those involving Gantt charts or project timelines.