There are two main things to look for in sensors: the sensor size and the resolution, in megapixels. It’s more important to get a bigger sensor than to get more megapixels.
This can mean one of several things depending on the context. Camera resolution is the number of megapixels on the sensor, lens resolution is how well the lens is able to resolve fine detail. Screen resolution is the number of dots on the screen and therefore how sharp/clear it looks.
This is the correct technical name for the individual light receptors on a sensor, though many people call them pixels because each photosite corresponds to a pixel in the final image. Each photoreceptor gathers light (photons) and turns them into an electrical charge (electrons) which can be measured.
The individual building block of digital images. Each individual pixel is a single block of colour, but when there are enough of them viewed from far enough away they merge to form the impression of a continuous-tone photographic image.
A fine interference pattern sometimes visible when you photograph fine patterns. It happens when these clash with the rectangular grid of pixels on the camera sensor. Actually, you almost never see it – most cameras have anti-aliasing/low pass filters to prevent, and it doesn’t seem to be an issue for those that don’t.