Foreshadowing: here are a few themes that we'll see over the quarter. We'll look at each of these in more detail at some point in the quarter.
An "algorithm" is the idea or plan of how to compute something - e.g. the algorithm to produce a bluescreen image from two images.
Code is made of the mechanical instructions the computer can follow. When you are programming, writing code, you are taking an algorithmic idea and translating it into code the computer understands.
The computer runs whatever code it is given mechanically. That is not the same as thinking! Writing code in CS101, you'll get a real appreciation for this idea.
Often the code you write will be quite short. The computer can run the short piece or code over millions or billions of data items. This is a powerful combination - the code has some insight in it, and the computer is good at applying that code massively.
Computer hardware gets significantly cheaper and more powerful year after year. E.g. 4 years ago your phone held 4 GB of data. Now for about the same cost it holds 16 GB (4x more). That's Moore's law.