Germans and most other Europeans count the number one with their thumb, while Americans count number one with their index finger.
In general, your middle finger is the longest. The ring and index fingers are equal in length as are your thumb and pinky.
The circumference of your hand as measured in inches across your palm and around the back of your hand is your glove size. This applies to many glove types such as surgical gloves. Typically gloves come in half size increments size 5 1/2 through 9. For example, if your hand measures 7 1/2 inches, you wear a 7 1/2.