Question: What are Flagella?
About the article "Bacteria", section "Movement".

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All kinetoplastids possess at least one flagellum, species in the order trypanosomatida have one and bodonina have two.
In kinetoplastids with two flagella most forms have a leading and trailing flagellum, the latter of which may or may not be attached to the side of the cell.
The flagella are used for locomotion and attachment to surfaces.
The base of the flagella are found in a specialised pocket structure which is also the location of the cytostome. 
Flagella types.
Zoospores may possess one or more distinct types of flagella: "tinsel" or "decorated", and "whiplash", in various combinations.
"Tinsellated" (also known as "straminipilous") flagella have lateral filaments known as mastigonemes perpendicular to the main axis which allow for more surface area, and disturbance of the medium, giving it the property of a rudder, that is, the purpose of being used for steering.
"Whiplash" flagella are straight, to power the zoospore through its medium.
There is also the 'default' zoospore, which only has the propelling, 'whiplash' flagella.
Both "tinsel" and "whiplash" flagella beat in a sinusoidal wave pattern, but when both are present, the tinsel will beat in the opposite direction of the whiplash, to give 2 axes of control of motility. 
Three types of flagella have so far been distinguished; bacterial, archaeal and eukaryotic.
The main differences among these three types are summarized below:  Bacterial flagella are helical filaments, each with a rotary motor at its base which can turn clockwise or counterclockwise.
They provide two of several kinds of bacterial motility.
Archaeal flagella (Archaella) are superficially similar to bacterial flagella, but are different in many details and considered non-homologous.
Eukaryotic flagella - those of animal, plant, and protist cells - are complex cellular projections that lash back and forth.
Eukaryotic flagella are classed along with eukaryotic "motile" cilia as "undulipodia" to emphasize their distinctive wavy appendage role in cellular function or motility.
"Primary" cilia are immotile, and are not undulipodia; they have a structurally different "9+0 axoneme" rather than the "9+2 axoneme" found in both flagella and motile cilia undulipodia.  
s in vascular plants.
Zoids are found in three types of vascular plants; ferns, cycads, and "Ginkgo biloba".
The zoids of each of these groups are large and multi-flagellated.
The mature spermatozoids of the fern "Asplenium onopteris" are 8 to 8.5 micrometers in length and contain 50 flagella.
The zoid of the cycad can be up to 300 to 500 micrometers long and can contain thousands of flagella.
The zoid of the ginkgo is approximately 86 micrometers long and also can contain thousands of flagella.
Because of the high number of flagella associated with both cycads and ginkgo, there has been some debate as to whether they are flagella or cilia.
Either way, cycads and "Ginkgo" are rare woody plants that produce motile gametes. 
Flagella are organelles for cellular mobility.
The bacterial flagellum stretches from cytoplasm through the cell membrane(s) and extrudes through the cell wall.
They are long and thick thread-like appendages, protein in nature.
Are most commonly found in bacteria cells but are found in animal cells as well.