(a) Pixel: the pixel is the smallest addressable screen element; it is the smallest unit of picture that can be controlled. Each pixel has its own address. The address of a pixel corresponds to its coordinates. Pixels are normally arranged in a two-dimensional grid, and are often represented using dots or squares.
Megabyte: the megabyte stores digital information or transmission with two different values depending on context

(b)One way that tourists on holidays can share digital photos with their family at home is that they can upload their photos onto a social networking site and then their family will be able to look at them. Another way that tourists on holidays can share digital photos with their family is they can upload the photos to the computer and then send them through email.

(c) One benefit in saving digital photos in jpg form is that jpg comprehends the photos and will wont lose much image quality. Another benefit is that jpg is very rare for losing digital images.

(d) Unlike traditional photos, digital photos are easily stores and distributed. Concerns mught arise from these developments because now pictures don't need to be sent through mail instead email and social networking. This might raise some concerns because people on social networking sites are allowed to see your pictures and it is unsafe for families. Some people don't need an account to see certain peoples profiles which is dangerous if your house is on the pictures or family and kids.