I know very little about olives but do know that I love them. Most of my experience in consuming them have been with the black or the green, but there are many, many more. Here is a little of the information I've found on these delicious little bites.
The fruit of the olive tree is available in more than 75 varieties. Olives are sold pitted and unpitted. Even though purchased pitted olives are more convenient to use in cooking than unpitted olives, pitting causes more of the olive to be exposed to the brine. This can cause the flesh to become softer and yield a different flavor. One way to remove a pit from an unpitted olive is to gently crush the long side of the olive with the heel of your hand, then pull out the pit.
Here are some of the more flavorful olives available.
Alphonso is a huge, deep-purple olive from Chili with soft, meaty flesh and a slightly bitter, sour taste.
Cerignalo's are huge, green or jet-black brine-cured olives with a lemon-apple flavor. This one is difficult to pit.
Gaeta is small, reddish-brown in color with a slightly earthy flavor.
Kalamata's are greenish-black-purple, brine-cured with a pungent, lingering flavor.
La Catalan is a brine-cured Spanish olive that's marinated with curry, celery, and pepper. It has a crisp, dense flesh and an assertive curry flavor.
Nicoise is a small, brownish-purple, brine-cured olive that's fruity and juicy, but not oily.
Nyon - Black, dry-roasted, tender olive with a slightly bitter flavor.