A red herring is a device used in mystery writing to throw the MC and ultimately the reader off the trail of the killer for a time.
Now, you can't have too many of them because eventually your reader will stop trusting you, but a good mystery does have some wrong turns along the way.
It makes the maze of clues more interesting to navigate.
A piece of evidence that turns out to be unrelated, some tid bit information that proves irrelevant, a seemingly 'off' character that is actually just strange and not necessarily the killer.
These are all red herrings that move the story along, create a diversion, but don't completely derail your reader.
The trick is to be subtle. Emphasis can be put on the "red herring cast member" by emphasis on their unusual traits, sketchy behavior, or just by creative description. Not everyone reacts to tragedy in the same way and sometimes lack of behavior can be shown as suspicious.
Whatever you choose to distract the reader, it needs to be adequately explained later in the book. For instance, at the time of a murder a mysterious car slowing and then accelerating past the victim's house may seem like a valid clue...until you learn that the neighbor's son is learning to drive a stick shift and the bizarre behavior has a plausible explanation.
Remember that a good mystery novel has at between 4 and 6 clues dispersed throughout with at least two very strong clues toward the middle and climax of the story. You want to lead your reader inexorably toward the culprit, but not too obviously -- hence a few strategically placed red-herrings.
Since mystery novels are usually highly structured and require a lot of planning, these clues and herrings are normally done in pre-write during the planning and blocking stage of writing. I have heard, however, of writers that actually write the story without knowing themselves who the killer will be...then, when they finally evolve the story to its conclusion, they go back and write in all the clues and red herrings.
However you choose to do it, writing a mystery novel can be an exhilarating ride. No one loves a chase more than I do...so I better get back to my WIP.
Until next time...Go Write!
Photograph by Laurel L. Russwurm