A multicolored Perseid shower
Credit: wikipedia

Meteor showers are usually named after constellation from which the meteors emerge.  Perseids showers seem to originate from constellation Perseus. it gets the name Perseids from the word Perseides, a term found in Greek mythology referring to the sons of Perseus.  Swift-Tuttle is a comet discovered by Lewis Swift and Horace Parnell Tuttle, It is the parent body of Perseids shower.

Perseid cloud

It is a stream of debris which stretches along the orbit of the comet Swift-Tuttle. This cloud is composed of particles ejected by the comet as it travels along its orbit. These particles vary in sizes some might be small while other are much bigger in size. Some particles from this cloud come in contact with our planet earth, which is then known as meteor shower or Perseids shower in our case. This dust cloud stays around the orbit of comet for hundreds of years, and is responsible for colorful display of meteor shower on to planets.

Radiant point

To any observer on earth, shower particles radiate out from a single spot in the sky. That spot is known as the radiant point, and meteor showers are mostly named after the constellations in which this radiant point of a shower seem to originate.

Formation of meteoroids streams and showers

Comets can produce debris, they are rock surrounded in ice, and ice could be in form of water, methane, ammonia or any other substances. Each time the comet orbit around the sun, some of its ice vaporizes and drag some sand, dust and pebbles along with it, this produce the stream. This stream spread all along the orbit of comet and the particles from this stream when come under the force gravity of the earth, changes into meteoroids shower.

Perseids shower activity

The shower is visible from mid-July each year, and its activity is on peak between August 9 and 14. While at peak more than 70 meteoroids per hour get to earth.

Does Perseids shower pose any threat to earth

Mostly small particles come in to our contact from Perseids shower, as these particles enter the gravitational field of earth,  they get battered to nothing due frictional force offered by the atmosphere of earth before reaching the surface of earth. People from all over the world are watching current Perseids shower of 2012. Conclusively Perseids shower doesn't pose any threat to earth.