I am a big believer in the glory of homemade stock. Grocery bought stock works just fine for many applications, but if you want to give your meals—particularly a nice soup or sauce—that extra restaurant-level complexity of flavor, homemade stock is the way to do it. You can make it from the scraps that you have leftover from making other things—just throw chicken bones and carrot tops and other trimmings into a zip-top bag in the freezer until you've collected enough to make a decent stock.
Of all the ingredients in the kitchen, vegetable stock or broth is one that is generally unloved by the culinary world. You can't get the gelatinous goodness that's the mark of a great chicken stock from celery and carrots, and so much vegetable stock tastes like little more than very salty water. But I, like so many people, have loved ones who don't eat meat, or would rather not, and so no matter what reserves of great fresh chicken stock I have in my freezer, I so often find myself reaching for a box of ho-hum vegetable stock to use in soups, sauces, and giving grains some flavor.