In its figurative senses, a red herring is either (1) a piece of information meant to mislead investigators, (2) a lead that turns out to be false (not necessarily based on an intentionally misleading piece of information), or (3) something that diverts attention from the main issue.
According to the Oxford English Dictionary, the term comes from an old hunting practice involving exercising horses by creating a false trail, literally of red herring, for the hounds and in turn the horses to follow. But the origins of the term are disputed, so don’t quote us on this.
Examples
Opponents cry partisan politics, claiming the election fraud scare is a red herring being used to disenfranchise voters. [Real Change News]
In my view, the debate about whether the dollar will be replaced by the yuan is a bit of a red herring because such a shift will not occur quickly. [Bloomberg]
Still, no word yet on whether the shocking final scene was indeed a bonafide reveal of the mysterious character — or just another red herring. [Us Magazine]
Gore described the volcano argument as a red herring and said that these sentiments arise from the role industry plays in politics. [New York Times]