Often in certain genres (such as landscape or macro photography), you need more depth of field and sharpness than is possible to capture in a single image. When that happens, you will want to turn to focus stacking. It is a relatively straightforward technique, and this fantastic video tutorial will show you a workflow for it using Lightroom and Photoshop.
Coming to you from Gary McIntyre Photographer, this excellent video tutorial will show you how to use focus stacking for sharper images with deeper depth of field. The idea of focus stacking is to take multiple images of the same scene (with the same framing) focused at different distances, then to combine these in post to create an image that is sharp from front to back. This gets around issues like diffraction, which arises when you use an aperture that is too narrow. Some landscape photographers use the hyperfocal distance, which can be quite an effective compromise that saves you extra work in post, but if you have a close foreground element or if you want ultimate levels of sharpness, you will want to turn to this technique instead, and it really is not that much extra work anyway. Check out the video above for the full rundown from McIntyre.