Here is the Outline from Wikipedia
The Single Transferable Vote, or STV, is a preference voting system designed to minimise wasted votes in multi-candidate elections while ensuring that votes are explicitly for candidates rather than party lists. In its most basic form, it works by allocating an elector's vote to their highest ranked candidate who has not already been removed from contention through either election or elimination.
Here's my Outline.
On the Ballot Slip instead of just putting a cross next to the candidate you want to win, you put a '1' next to your first choice candidate, and then you can put a '2' next to your second choice, etc. You do not have to vote for every candidate, although you can be tactical and put the most hated candidate right at thee bottom of your list.
A quota now has to be reached and the most common is the Droop Quota which is simplified as
Now the votes have to be counted
Process A: Top-preference votes are tallied. If one or more candidates receive at least as many votes as the quota, they are declared elected. After a candidate is elected, she may not receive any more votes.
The excess votes for the winning candidate are reallocated to the next-highest ranked candidates on the ballots for the elected candidate. There are different methods for determining how to reallocate excess votes.
Process A is repeated until there are no more candidates who have reached the quota.
Process B: The candidate with the least support is eliminated, and his votes are reallocated to the next-highest ranked candidates on the eliminated ballots. After a candidate is eliminated, he may not receive any more votes.
After each iteration of Process B is completed, Process A starts again, until all candidates have been elected or eliminated.
I hope this gives you a gist of how it works.
The Scottish Parliament passed a bill which means the first-past-the-post voting system for local elections will be replaced with the single transferable vote (STV) and this could be in place by 2007. Charles Kenndy (leader of the Lib Dems) has also pushed for this and would like to see it implemented here as the proportion of Lib-Dem voters is not proportional to the seats they gain in parliament.
I suppose at the end of the day there will never be a party with 100% backing but I suppose it's better than one with only 35% of the votes cast (not even 35% of the population. I suppose it would be fairer if everyone had to vote, but you can't force anyone to do anything.
Well that's the end of that very interesting post. I promise a more fun one later.