Vote of No Confidence (in government)

[LadyBlaBlah]

Out of genuine interest, could someone explain to me how this works?

What does it mean and how does it come about?

So many times a year there are debates sponsored by the official Opposition. This debate could be worded that 'This House has no confidence in Her Majesty's government'.
This is then voted on and if carried the government is forced to resign.
Similar debates can be instigated as amendments to other debates.

When Prime Minister, John Major actually instigated a no-confidence debate on his own government. The debate was entitled 'This House has confidence in the government's recommendations regarding the Maastricht Treaty' or something like that.
Basically, he threatened to call a general election if the Maastricht Treaty was not approved.