The Honda strut is the main vibration dampening component in independent suspensions on vehicles from this manufacturer. This is a hydraulic part that has replaced the shock absorber found on older style suspension systems.
The bottom of the strut is mounted to your Honda's steering knuckle where the control arm is also attached. The top of the strut is bolted to the top of the wheel well which can be seen from under the hood or in the trunk.
The Honda strut not only replaces the shock absorber, but also incorporates a built-in coil spring that was usually not seen on older models. Because of this coil that is built into this component, special tools and equipment is required if you are going to be removing and replacing parts of the whole assembly. This is so the coil portion can be compressed in a safe manner.
The strut on your Honda can be tested to see if it has excessive wear on it in the same manner that the old style shock absorbers are tested. This is done by compressing the corner of the car and watching how many times the body moves up and down when the pressure is released. If the body moves up them back to a resting position then this suspension component is in proper working order. If it continues to move up and down then the strut is showing signs of being worn and replacement is advisable. Both sides of your Honda should be tested in this manner, one right after the other.
This suspension component can also leak hydraulic fluid and be in need of replacement on your Honda vehicle. This can be spotted with a visual inspection of the shaft on the suspension component.