Trail blazes are rectangular markers that are prominently located on trees or poles, and sometimes painted on large rocks. Their purpose is to guide hikers along a trail without getting lost. A particular trail is blazed all in one color, and many colors of trails can be found in one park.
Most blazes consist of one rectangle, which means you are following the trail. When there are multiple blazes on a tree, the meaning changes. This chart shows how the placement of multiple blazes modifies their meaning: