Article: Open up the oven, pull out the rack a bit, and push the sides of the cookie very lightly with a spatula or your finger. If the edge stays firm and doesn't fall inwards, then your cookies are done. If you leave a noticeable indention, then your cookies likely need a few minutes more in the oven.  This is an especially good method to use with dark cookies, such as chocolate or gingerbread, where coloring isn't the best indication of doneness.  If you choose to use your finger to test, make sure to be very careful or you could get burned by the baking sheet. If you are working with a fragile cookie, like shortbread, test them by pressing lightly into the center instead of the edges. This will lower the likelihood of them breaking up upon contact. Pull open your oven and slide your metal spatula halfway under a single cookie. Lift up just a bit and check the coloring of the cookie's underside. The cookie should appear light brown or golden in coloring and firm in texture.  Be very careful when lifting or you could split the cookie in half. This method works well for sandies, spritz, and other pale colored cookies. It's sometimes hard to test the doneness of bar cookies because they are so dense and often dark in coloring. Get a wooden toothpick or skewer and push it into the bar. Keep going until you reach the halfway point of the cookie. Withdraw the toothpick. If there are lots of crumbs or batter on the wood, then the cookies are not quite done. It's important to use wood skewers or toothpicks. Metal ones do not work as well as the crumbs will simply slide off.

What is a summary?
Press the edges with your finger. Lift the cookie up to check the bottom. Insert a toothpick into bar cookies.