Summarize this article in one sentence.
The sensor is the element inside the digital camera that determines how much light it uses to create a picture. In general, the larger the sensor, the better the image quality will be. If you are a beginner and are looking for a digital camera for personal use only, the small sensor on most basic compact cameras (about 1/2.7 inch or 5.37x4.4-mm) should suffice. If you are a professional photographer, however, you will likely need to look for at least a 1-inch or 12.8x9.8-mm sensor.  Assessing the size of the sensor can be difficult because there is no uniform form of measurement. For example, a digital camera with a good-sized sensor might describe the sensor as 1-inch or 12.8x9.8-mm. The best way to interpret what this means is to use the internet to consult a conversion chart, which is readily available on many websites.  While advertisers tend to focus on megapixels as the barometer for image quality capabilities, the physical size of the sensor actually matters much more than the megapixel count. For example, a basic beginner’s compact point-and-shoot digital camera may have the same megapixel count as an expensive DSLR, but the image quality will not be the same because the DSLR will likely have a much bigger sensor. An optical zoom lens uses real optics to make objects that are far away look closer. When you are comparing digital cameras, consider how many long-range images you will need to take. If you plan to use your camera for images of the moon or sporting events, for example, you will likely want to choose a camera with at least a 24x optical zoom lens.  While some basic point-and-shoot cameras may have a long-range optic zoom lens, you will likely need at least a zoom compact digital camera if you determine that you want to be able to get good quality long-range images. While increasingly rare, some cameras do still come with a digital zoom lens instead of an optical zoom. Digital zoom lenses tend to produce images that are grainier and less clear than images produced with an optical zoom lens. Nowadays, though, the majority of even the most basic point-and-shoot cameras come with at least a 3x optical zoom lens. Still, it is worth it to check. Most digital cameras these days come with built-in flashes with adjustable brightness that are perfectly sufficient for beginners and even more advanced hobbyists. If you are looking to take high-quality indoor photos and have more creative control over the lighting, however, you will want to select a camera with an external flash attachment capability. External flashes are usually sold separately and can cost anywhere from $12 for a basic compact to several hundred dollars for a DSLR. When comparing digital cameras, assess how much control you want to have over the light conditions (controlled by the ISO), depth (determined by the aperture), and shutter speed. Most digital cameras come with an automatic mode where the camera determines the ISO, aperture, and shutter speed for you. However, if you want more creative control over how your image turns out, you will want to choose a digital camera that also contains a manual mode.  Some more advanced compact digital cameras come with a manual mode option, while almost all DSLR and medium format cameras will have a manual mode option.  Digital cameras that contain a manual mode tend to be more expensive that those without it. The frame rate is the number of images a camera can take in one second. While there are some very slow digital cameras on the market, it is generally recommended that you choose a digital camera that takes at least 5 frames per second. That way, even if you are a beginner looking for a very cheap and user-friendly option, you won’t miss capturing any of life’s important moments.   All digital camera types can come with high or low frame rate speeds, so it is important that you check the information for the particular model you are interested in. If you plan to take a lot of action images (such as your child playing soccer), you will likely want to select a camera that takes 10 to 25 frames per second. Be aware that these options might be a bit more expensive than the lower speed options. While almost every digital camera (including basic point-and-shoots) can shoot HD videos, there are high-end mirrorless and DSLR cameras available that have the capability to shoot film-quality videos. These cameras contain higher frames per second rates (60 and up) and better video stabilization than most cheaper, more compact models. If you are looking for a camera with high-quality video capabilities, pay closer attention to the frames per second rate than the resolution. Several compact cameras, for example, may advertise that they can shoot video at 4K Ultra HD resolution, yet may only record at 15 frames per second.

Summary:
Determine the sensor size you need to get the image quality you want. Get a longer optical zoom to capture longer range images. Invest in an external flash for more control over lighting. Select a digital camera with a manual mode to control the exposure. Look for higher frame rate speed if you want more image options. Choose a mirrorless or DSLR for more video recording capabilities.