A very quick usage note based on an error I see quite a lot.
“Economic” is an adjective that means “related to economics or the economy.”
As in: “I had to sell my house for economic reasons.”
Or: “Universities that invest in sports enjoy certain economic benefits.”
“Economical” (note the last two letters) is an adjective meaning that something is affordable or doesn’t cost or use a lot of money.
As in: “My new compact car is very economical.”
Or: “I replaced my old light bulbs with more economical fluorescent bulbs.”
Or: “Switching to solar energy is a very economical choice in the long run.”
You can also refer to a person who doesn’t spend a lot of money as “economical,” but I think this is a bit less common and I tend to avoid it.
As in: “Josh is a very economical shopper.”
Just to complicate things, the subject you study at university is “economics.” Note the final letter.
As in: “I took an economics class last semester.”
And: “I need to buy an expensive economics textbook.”
Quite a lot of students forget that final “s” when they write personal examples in their essays!