How does a match stick be lit up with a magnifying glass?

With a magnifying glass, we are able to focus the sun rays onto a point.
When we place the head of the matchstick on the focus point,
the heat from the rays will light the match stick, causing it to light up.

The head of the match stick contains either phosphorus or phosphorus sesquisulfide,
which will ignite with the heat created from friction or just direct heat.
The sun rays focusing on the head of the match stick is high enough to ignite it.

The above picture is an example of how a magnifying glass is able to focus onto a point,
which is the butterfly.

Picture taken from http://www.goalfinder.com/product.asp?productid=26

Tan Chee Yoong