On most cameras, you can manually adjust the aperture and shutter speed. This can reduce the amount of time between when you press the button and when the shutter opens. Most cameras also have a fully automatic mode that adjusts the settings, including the focus, for you. You can take lots of good, clear pictures with this mode. Many cameras also have several presets for capturing portraits, fast action or outdoor scenes.
But automatic exposure might not be best for every situation, so understanding f-stop, shutter speed and presets can make a huge difference in how well your camera works for you. Being able to set the exposure on your own will also let you cut down the amount of time between when you press the button and when the shutter opens. In other words, you can take the picture you want before the moment passes. You can learn more about setting exposure by taking several pictures of the same scene using different settings and seeing how the finished product changes.