What,exactly is seltzer?!

Question: I have an american cocktail recipe book,and some of the recipies ask for seltzer.
What can I use it's place,as seltzer isn't available here in the U.K?

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Answers: I have an american cocktail recipe book,and some of the recipies ask for seltzer.
What can I use it's place,as seltzer isn't available here in the U.K?

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Seltzer, carbonated water, club soda and mineral water all similar enough to substitute.

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It's just carbonated water, isn't it?

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