Megapixel
A megapixel is a unit of measurement equal to one million pixels. Megapixel count is typically used to describe the total number of pixels a digital camera's sensor can capture and the resolution of the resulting digital photographs. A camera sensor with a higher megapixel count can capture larger, more detailed images.
An image or sensor's megapixel count is found by multiplying its number of pixels horizontally by its number of pixels vertically, then dividing by a million. For example, the camera sensor in an iPhone 11 captures images at a resolution of 4,032 x 3,024, which results in 12,192,768 total pixels or roughly 12 megapixels. A Canon EOS R50, on the other hand, captures larger photos at a resolution of 6,000 x 4,000 to produce 24-megapixel images. Higher-resolution images require more storage space on the camera's SD card or internal storage.
When viewing images on a computer or mobile device's screen, you may not be able to notice all of the detail captured by a high-megapixel sensor. For example, a 10-megapixel image completely fills a 4K display, so going up to 24 or 48 megapixels requires zooming out to see the whole thing, losing some detail as pixels merge together. A higher resolution is more helpful when printing photographs; for example, a 24-megapixel image printed at 300 DPI is roughly the size of a standard 12" x 18" photo. A high megapixel count becomes very important when editing and cropping photos since you start with as much image data as possible; you can always resize an image to make it smaller and easier to share with others later.
While a higher megapixel count generally means a more detailed image, other factors also significantly affect the final results. The quality of the lenses and other optics in the camera affects how sharp the image that reaches the sensor is. The sensor's physical size (independent of its pixel count) affects how much light it receives, reducing noise and producing better low-light photos. Adjustable camera settings like shutter speed and ISO can affect an image's sharpness and brightness. Finally, external factors like the amount and quality of light are always crucial to capturing a good photo.