Snare drum roll
A common snare drum roll is the closed roll. The closed concert roll (orchestral roll, buzz roll, or press roll) is performed by creating 3 (or more) equal sounding bounces on each hand alternating right to left, repeatedly and quickly. The aim of a closed roll is to reproduce the effect of a sustained note on an instrument which inherently produces a short, staccato sound.  Because a multiple bounce stroke on a drum head loses energy, and volume, with each successive bounce, it is necessary to use special tactics and techniques to mitigate the loss of sound and cause the repeated to notes to sound even. This involves the arm, the wrist, and the fingers. One way to mitigate the loss of sound is to overlap the 3rd bounce from one hand with the first bounce of the next in the manner of a Flam Tap, only much much faster and smaller. The loud first bounce occurring closer to the quiet 3rd bounce from the preceding hand give the illusion that the bounces have a more even volume.
There are many interpretations of concert rolls and while the variations result in a similar rolling sound, there are subtle audible differences. One major point of differentiation between rolling techniques is between Metered and Unmetered rolls. Metered rolls require the players arms and wrists to play in time with the beat of the music and so a regular subdivision, such as 8th note triplets, 16th notes, or 16th note triplets must be chosen and maintained. The drawback of metered rolls is that the ideal rolling speed (for the player, the room, the sticks, and the instrument) may lie between exact subdivisions, depending on the tempo, and the sound quality may vary by tempo. The benefit is that it makes all the rolls fit neatly into the music in time and is easier to count. Unmetered rolls require the player to perform the best possible sounding roll they can, whether or not the arm movements correspond to the musical tempo. The drawback to this approach is that the player must count the beats of the music independently to, and in complete disregard of, the speed of the roll and the corresponding arm motion. The benefit is that the roll sounds optimal and smooth at any tempo. The metered closed roll should not be confused with the open or measured roll, as described below. 
Examples of Drum rudiments that are similar to, or precisely like, a concert closed roll include:
- American - Multiple Bounce Roll and Triple Stroke Roll
- German - Druckruf 
- Scotch - Buzz Roll, stroked rolls 5 through 25 (metered closed rolls in Scottish tradition), and Trizzlet 
- Dutch - Ra stroke 
The open roll (or "double-stroke roll") is played with double strokes alternating between the left and right hands. Using a forearm stroke for the first and the fingers for the second stroke, the 2 strokes can be made to sound identical. This produces a near-continuous sound when the technique is mastered. In rudimental drumming, open rolls, consisting of double strokes, are often measured out to a specific number of strokes. A 3 stroke roll is the shortest possible open double stroke roll, but is commonly referred to by the specific name "Drag," "Ruff," or "Half Drag." Typically, any roll with an odd number of strokes is played with a single accent and any roll with an even number of strokes is played with 2 accents. This patterns holds for the 5 Stroke, 6 Stroke, 7 Stroke, 9 Stroke, 10 Stroke, 11 Stroke, 13 Stroke, 15 Stroke, and 17 Stroke Rolls of the PAS 40 rudiments. Note that some numbers between 5 and 17 are missing. These additional rolls are possible and are taught in modern hybrid drumming and in older pre-NARD rudimental systems, as well as those from other countries, notably the Basel and Scotch cultures. For example, the 8 Stroke Roll is present in the Moeller Book from 1925 but is lost in later publications. The 4 Stroke, 8 Stroke, 12 Stroke, 14 Stroke, and 16 Stroke are rare but all exist in official published sources. The Scotch Pipe Band style has a rudimental roll up to 25 strokes. This provides the drummer with a consistent set of rolls from 3 to 17 plus the 25, with any other number being an extrapolation from this system.
Other than the open roll, there are many other rolls and rudiments that sound like rolls when they are played fast enough (like the freehand technique or single paradiddle).
In the table below, lower-case letters represent grace notes (drags, flams etc.) and hyphens represent rests.
|Triple-stroke roll (or French Roll)
Also, the six-stroke roll is often used in snare solo and marching percussion situations and is a favorite for jazz and rock drummers. It has four variations; each note is equal in length and consists of two double strokes (RRLL) and two singles (R L). The strokes are most commonly taught as (RLLRRL).
Rolls on timpani are almost exclusively single-stroked. Due to the instruments' resonance, a fairly open roll is usually used, although the exact rate at which a roll is played depends greatly on the acoustic conditions, the size of the drum, the pitch to which is it tuned and the sticks being used. Higher pitches on timpani require a faster roll to maintain a sustained sound; some timpanists choose to use a buzz roll on higher notes at lower volumes; although there is no definite rule, most timpanists who employ this technique do so on a high "G", and above. In the end, it often comes down to the discretion of the timpanist.
These are similar to the timpani rolls in that they are done nearly the same way and are both single-stroked. Yarn mallets usually can be rolled much more easily on a marimba than plastic ones can be on a xylophone, because the extra reverberation of a marimba will mask the silent gaps between strokes. For this reason, the rolls can be much slower and still effective. But for xylophone and orchestra bells a much swifter roll is required, especially for rubber or plastic mallets. A brass mallet used with orchestra bells will add extra vibration to aid in the smoothing of the sound.
To get these faster rolls, percussionists (keyboard, snare and timpani) all often use the muscles of their fingers instead of those of the wrists. The fingers have a shorter rotation length and can move faster with less effort than the wrist.
Fulcrum roll/Gravity roll/Freehand roll
The fulcrum roll, or freehand roll, is a roll in which the rim of the drum momentarily replaces the original finger-created fulcrum. Thus is qualifies as a dual-fulcrum or multiple-fulcrum stroke. The initial stroke creates contact with the drum head in a relatively normal manner. Immediately subsequent, at the bottom or end of the down stroke motion, the rim is contacted approximately 1 inch in front of the thumb and forefinger. Contact with the rim rocks the front portion of the stick upwards from the point of contact with the rim. At this moment, the wrist is located just below the rim and the bead is a couple inches above the head. From the bottom of the down-stroke, the hand is then raised for the upstroke. While the hand raises, the bead of the stick is returning toward the head after its bounce off the rim. As the raising hand and falling bead reach the same height, the head is struck for the second time. This creates two beats contacting the drum head out of a single stroke motion of the arm. The precise moment of contact with the rim momentarily creates a new fulcrum at the drum stick's physical point of contact with the rim. This is one of the easier and more commonly used forms of a "one handed roll". When executed with precision, this doubling of contact means 16th notes can be played while the arm only strokes 8th notes, or 32nd notes can be played while stroking only 16th notes. The technique is also known amongst many drummers as the gravity blast, though gravity is not required as the technique can be performed inverted, sideways, or in a gravity free environment.