Parts diagrams can be a very useful aid to understanding how a vehicle or sub-assembly goes together/ comes apart or what something is comprised of, or just what parts are available to buy as spares! Whilst I would never 100% trust the part numbers quoted (and indeed there are some obvious errors and diagrams that unfortunately have been catalogued incorrectly so they don't open properly when you click on them), they can be a very helpful guide.

Here are the links:

******EDIT JAN 2017******** - The EUcat website with the Ford parts diagrams in the below 3 links seems to have been offline for several weeks now, hopefully it hasn't gone the same way as Partsbase did!

Ford (covers most models)
Mk1 Galaxy
Mk2 Galaxy

Alternative site to the above with links to parts diagrams for Ford and a range of other marques here. Credit to joka for this one!

VW Sharan (all years) plus other VW models

And

A load of other manufacturers!

******EDIT MAY 2016********- Partsbase, whose parts diagrams I linked previously for VW and other manufacturers unfortunately appears to have disappeared from the web! I have linked an alternative site with diagrams for a range of manufacturers.