Final answer:
The use of a pinhole to limit out-of-focus light is a key feature of confocal microscopy, enhancing image resolution by allowing only light from the focal plane to reach the detector.
Step-by-step explanation:
The incorporation of a small aperture, or "pinhole", near the detector that limits the transmission of out-of-focus light emitted from the specimen is an important feature of confocal microscopy. This technique employs a focused laser beam that scans across the specimen, and the pinhole is situated such that only the light from the focal plane (the plane exactly in focus) reaches the detector. This setup results in much higher resolution images with greatly reduced background compared to other types of microscopy, because out-of-focus light is minimized. Confocal microscopy is particularly valuable in fields like cell biology, where it's essential to visualize the interior of cells in as much detail as possible.