A string trimmer uses a monofilament line to cut through grass, weeds, and small, woody plants. By spinning at a high speed, a cutting head generates enough centrifugal force to hold the line out at a stiff, horizontal angle, making cutting possible.
A line trimmer is a great gardening tool when it's running right. If the engine sputters or vibrates, it may be time for a good tune-up. If that doesn't help the engine run smoothly, then you may need replace the carburetor or other engine parts.