Tree stumps may not seem like a big danger most of the time.  But they can become a problem in different circumstances and can even slow down development if you are having an established extension or yard.  Stumps are the debris left when a tree is felled that is still connected to the root system.  They are usually close to the ground, but stick out a bit as they are difficult to remove without specialized equipment.

Old stumps can also look unsightly after a while, as they tend to attract mold and fungus.  This can even spread to neighboring plants and trees, causing rot and other problems.  They can prevent any work in the area, such as laying a patio or an extension, until they are removed, and there is always the chance that the tree roots are not dead and the tree will grow back.