Can somebody explain 'kettle caramelisation'?

[Spook]

Matt's thread on Fursty Ferret in 'Recipes' mentions the Badger brewers talking about 'kettle caramelisation'.
Matt also talks about it in the same thread and mentions reducing the liquid through boil by a few litres to achieve it.
What is it?
Why is is used?
What is the result of doing it?

Thanks in advance guys,

Spook.

[Matt]

Hi Spook,

Caramelisation is boiling wort longer to break down some of the sweet compounds to make caramel flavours. In a home brew setting it is common to draw off a couple of litres of your first runnings and boil on a hob, down to half a litre, taking care not to scorch (can be a bitch).

It's akin to mixing sugar and water and boiling down to a thick caramel syrup.

Matt

[Martin G]

This seems to give a good background to the previous post.
http://en.m.wikipedia.org/wiki/Caramelization

[darkonnis]

depending on batch size it can be a pretty expensive way of doing it. You can add the belgian dark candy sugar and get similar results from what I've read.