Splitting the vote - definition

"Splitting the vote" usually applies to a situation with three viable candidates. (A,B,C)  One of the three (A) is considered stronger (usually the incumbent) than the other two.  In order to beat A, votes would need to be concentrated on only one of the remaining two (B).  By casting any votes for the weakest candidate (C), this is considered "splitting the vote". 
(To explain this further if you're still not with me:  More people are already in the A camp (for simplicity's sake, say 50%.  That leaves 50% for the B&C camp together.  If everyone in the BC camp voted for B, then there'd be a tie between A&B.  However, if anyone votes for C, then you are SPLITTING the BC vote: B has less than 50%, C has way less than 50%, so A then wins with 50%.) 

Strategic Voting

Strategic/tactical voting is when you vote for a candidate that is not your first choice, in order to prevent someone else from winning.

Strategic voting is controversial.  Many would advocate that you should vote with your conscience - i.e. vote for who you think would do the best job, regardless of any politics.  Others, however, would say that you are throwing your vote away when you do this, particularly when it's a two-horse race.  Maybe you like Candidate C, but are aware that there's no way he'll win, and you realise it will be either A or B.   So, do you forget about C and pick who you'd rather win between A or B?  Or do you use your vote to support Candidate C and show that there aren't only two choices? 

I'd like to be clear that I am not advocating one method or another, I just want to ensure everyone knows what it means.  Be aware that people in your ward might be considering it (like mine - Ward 7!)

What Other People Think

For further info, I tried to find some opinions for either side.  Although not regarding this particular election; both sides are presented well. 

For strategic voting
Against strategic voting