Which items are less than 90 degrees?

Items that are less than 90 degrees typically include acute angles, which measure between 0 and 90 degrees. In geometric contexts, shapes like triangles can have angles that fall into this category, particularly acute triangles where all angles are less than 90 degrees. Additionally, certain tools or instruments, like protractors and compasses, can be used to measure or create angles less than 90 degrees.