how many different typeof ladders are there?

Question

thats the ones with rungs that you see window cleaners use

Answer 1

Most people will encounter a situation in which their reach must exceed their grasp. The solution to this problem is often found in the form of ladders. Some ladders may only elevate the user a few feet from the ground, while others provide access to a third story roof. Then there are the modern adjustable ladders, which can provide everything from scaffolding to painting support. It's all a question of need, storage and portability.
Some of the simplest types of ladders are called step ladders or A-frame ladders. A small step ladder may be used indoors to reach upper storage spaces or to hang artwork on the walls. A-frame ladders are often used to elevate the user perhaps four feet or so from the ground. Step and A-frame ladders use fairly wide treads (steps) for stability and usually fold together for easy storage. Step and A-frames ladders are generally not expensive and should provide enough elevation for routine tasks around the house.
For those who must reach the sides of their homes for painting or roofs for maintenance, extension ladders are a must. Extension ladders may fold down to the length of one segment for storage, but can be telescoped to reach many feet in the air. Unlike the self-supporting A-frame design, extension ladders are often propped against walls or other sturdy surfaces for support. The legs have adjustable foot pads which provide level contact with the ground. The rungs of many extension ladders are round and narrow, unlike the wide and flat treads of step ladders. Wearing proper footwear is essential when working with extension ladders, since the rungs can become oily or wet over time.
A special form of extension ladder is the roofing ladder. A regular extension ladder may lean against a wall or tree, so the ends may be squared off a bit. Roofing ladders, on the other hand, should extend a few feet past the edge of the roof. For extra security, these ladders often have hand grips or special hooks on their top ends. Roofing ladders can be used as regular extension ladders, but extension ladders should not be used as roofing ladders. They simply lack the added security needed for safe roof work.
Just as important as the types of ladders are the materials used to make them. Originally almost all ladders were constructed from wood, but today's consumer can select from wood, aluminum or fiberglass. Wood is still preferred by many for its durability, low cost and non-conductivity. Wooden ladders can be relatively heavy, however, and prone to damage from insects and weather exposure.
Aluminum ladders are valued for their portability, strength and resistance to climate. However, any metal ladder can become a hazard when exposed to electrical sources. Aluminum also tends to bend easily under pressure, so aluminum ladders can become twisted and unstable. Aluminum ladders are ideal for indoor usage and outdoor projects away from power lines and corrosive salt water.
The newest ladder material is fiberglass. Fiberglass ladders are non-conductive, which makes them better suited for outdoor work and roofing. Fiberglass is also resistant to insect damage and exposure to the elements. Unlike aluminum, fiberglass frames won't bend easily under normal pressure, although they may snap suddenly under stress. Fiberglass is not lightweight, however, and long-term stability data is not available yet. Aluminum and fiberglass ladders have become much more common than wooden models in recent years, so the choice of material often comes down to a matter of portability and longevity. Step Stool Ladders Alaco Ladders Stairway Slope Ladders Cosco Ladders

Answer 2

Here is a link on all types of ladders and how to use them safely