A dessert is something sweet that you eat, usually after a meal. It can be any range of things: puddings, cakes, fruit, pies, cookies... If it's sweet, it counts. :) A pastry is a dessert that is at least partly made with dough (flour, sugar, etc.) and is baked. A pie counts because it has a crust and is baked, for example. Tapioca pudding does not because it has no dough and is cooked on a stovetop. A cookie in the U.S. Is a small, round, sweet, dense baked product made from a usually heavy and rich dough. It can be baked to be crunchy or soft. Some famous branded examples are Oreos (crunchy) and Mrs. field's Chocolate Chip cookies (soft). Copy and paste this link to see some pictures: https://www.google.com/search?q=mrs.+fields+chocolate+chip+images&ie=UTF-8&oe=UTF-8&hl=es&client=safari My understanding is that outside of the U.S., the word "biscuit" is used to mean the same thing as cookie. A biscuit in the U.S. is a savory quck-bread (no yeast) made of dough that uses little or no sugar, and is usually baked to be fluffy. We eat these along with meals. Here are some pictures: https://www.google.com/search?q=bisquick+biscuit+images&ie=UTF-8&oe=UTF-8&hl=es&client=safari

I am not a cook, but I like to eat! "Pastry" is a broad word that includes rolls, cookies, cakes, etc. Generally somewhat sweet. "Cookie" is very specific. If you google image "cookie" you will know what it is. It is a sweet biscuit. "Dessert" is simply the word for the part of the meal you eat after the regular food. You follow up the main meal with something sweet. "A dessert" includes any type of food you would eat for dessert. A "biscuit" is like a cookie, but not as sweet. You may find that these terms differ depending on geographic location.