Voting tactics
Why is it that only people in a jurisdiction where they use a broken voting system (such as, say, first past the post or instant-runoff) know about 'tactical voting'? Frankly, I'd be surprised if anyone in my family even knew what it means to vote 'tactically'.
For reference, Belgium uses proportional representation throughout. In fact, it was a Belgian guy who invented proportional representation.
oh well.
I'd expect because the concept is discussed only in countries that have non-standard systems.
As to belgians, they may not know the name, but they certainly know the concept. After all, Belgium is the country where some French-speaking Brusselaers (inhabitants of Brussels) vote for a random dutch-speaking "democratic party" just to offset the Vlaamse Blok^W^WVlaams Belang. If that's not tactical voting, I don't know what is.
They do it because it won't impact the French/Dutch speaking balance in parliament (hardcoded in constitution).