While canning lids come in just 2 sizes, standard and wide mouth, canning jars come in many different shapes and sizes which leads to the question, "Why so many jars?"
And the answer is, different foods like different jars.
Breaking jars into the two main categories and discussing by size, here are my recommendations for what jars to use for what applications.
Standard Mouth Jars.
These jars take the smaller of the two lid sizes and are usually straight sided until the 16 ounce size which has "shoulders". The replacement lids and rings are slightly lower in price so over the long run, it is cheaper to can in the standard mouth jars.
2 ounce--Great for powerful goodies like Bacon Jam or Plum Marinade. Also good for dry spice rubs and other special seasonings.
4 ounce--For Jams, Jellies, Marinades, Hot Sauces and Salsas.
8 ounce(half-pint)--Jams, Jellies, Salsas, Fruit Butters, Relish, Tomato Paste, Pizza Sauce and single servings of fruit(to pack in lunches).
12 ounce Quilted Crystal--Jams and Jellies, Pickled Asparagus, Pickled Beans and other pickles prepared in long slim sticks.
16 ounce(pint)--Usually this is the smallest size of jar that has "shoulders" which are useful to help hold fruits and vegetables, that might tend to float, under the level of the liquid. Use these jars for apricot halves, plum halves, tiny pickled whole peppers, brandied fruits, spiced apples, tomato sauce, fruit spreads for larger families.
32 ounce(quart) --Whole & Chopped Fruits, apple sauce, dill pickles, fruit juices and fruit juice concentrates, pie filling.
Wide Mouth Jars.
These jars take the larger of the two lid sizes. The lids for these jars are slightly more expensive but these jars are easier to fill without making a mess and are very desirable in cases where food is to be "arranged" as it is put into the jars. Also in most cases, wide mouth jars are as comfortable in the freezer as they are in the pantry and can be used as a replacement for plastic containers.
8 ounce(Freezer-Safe)-- Frozen Soups, Canned Relish and Sauces.
16 ounce(Freezer-Safe) Thick Sauces, like Apple Butter, that will be spread with a butter knife. Frozen Soup for 2 people.
32 ounce-- Whole & Chopped Tomatoes, Pickles.
64 ounce(half-gallon) Fruit Juices, Fermenting, Dry Goods Storage.
These, rather expensive, jars are great for gift-giving.
"Elite Platinum" 4 ounce(half-pint)-- Dipping Sauce, Pesto, Jams & Jellies to be given as gifts.
"Elite Platinum" 8 ounce(pint)--Hostess Gifts of Homemade Pickles & Sauces.