When a tree or large shrub is taken down there will is always a small part of the tree left under the ground, including its roots, this is known as the stump.
A stump can be left in the ground and not cause any problems but can provide homes for insects and bugs.
On occasion it may be necessary to treat the stump to prevent it growing again.
When stump grinding maybe necessary
If your looking to re-plant in the same area.
If a new building or construction is being built.
If the stump may cause a safety hazard.