I’ve heard something about smart contracts, but I don’t fully understand how it works. A friend recently told me how he invested in DeFi through such contracts, but at first he had problems understanding what to do and how to do it. Eventually he got involved somehow quickly, and now brags all the time about how he manages to make money with them. I wonder how smart contracts work and are they really as reliable as they are described? Have any of you used them or know more about them?