Many people describe computers as "complex" machines. What can this mean

''Why people describe computers as complex machines. A computer is a general purpose device that can be programmed to carry out a set of arithmetic or logical operations. [ Since a sequence of operations can be readily changed, the computer can solve more than one kind of problem. Modern computers based on integrated circuits are millions to billions of times more capable than the early machines, and occupy a fraction of the space.[2] Simple computers are small enough to fit into mobile devices, and mobile computers can be powered by small batteries. Personal computers in their various forms are icons of the Information Age and are what most people think of as "computers." However, the embedded computers found in many devices from MP3 players to fighter aircraft and from toys to industrial robots are the most numerous.'' This was found on a unknown website.