Pickles are divided into two main categories: fresh-pack and fermented. Fresh-pack pickles are made using an acidified brine, while fermented pickles use a salt-water brine and make use of bacteria and yeast present in the environment to turn them sour during fermentation. Once pickled, all are ready to eat immediately, but the pickling process is more extensive for fermented pickles, which are made in the traditional way.
Genuine dill pickles, kosher dills and Polish-style dills are the most common examples of fermented pickles. These pickles are submerged in a brine for many days until they develop enough lactic acid through fermentation to turn them sour. Fermented pickles can come in many other varieties as well, but typically are labeled as fermented or naturally fermented and do not contain vinegar.
Some common types of fresh-pack pickles include quick dill pickles and overnight dill pickles, as well as many other types of sweet pickles, such as bread and butter pickles, candied pickles, sweet hot pickles, gherkins and no-salt sweet pickles. These types of pickles all use an acidified brine such as vinegar or lemon juice to quickly flavor the pickles, and all retain a nice crunch.
In the United States, the term pickle typically refers to pickled cucumbers, but in other countries, many other vegetables and fruits are pickled in a similar manner and considered to be pickles. These include eggplant, chiles, mangoes, carrots, cabbage, radishes, turnips and more.