Estimation is when we make a guess about something using a small group of information. For instance, if we want to know how tall all the grown-ups in a city are on average, we might pick a few grown-ups at random, measure how tall they are, and then use that average to guess how tall all the grown-ups in the city are. Hypothesis testing is like doing an experiment to check if a company's claim about their product is true. Let's say the company says their product can lower blood pressure by 10 points. To test this, we would ask some people to try the product and measure how much their blood pressure goes down. Then, we would compare the results to see if the average decrease is different from 10 points. The confidence interval is a range of numbers that we think a certain value might be in. We get this range by looking at a smaller group of things and making a guess about the whole big group. We are not 100% sure about the exact number, but we are confident that it is in this range