Understanding the Lingo
Within the genre, there are sub-categories that describe certain types of mysteries. Some people like hard-boiled detective stories; others love cozies.
COZIES
A cozy is the type of book that makes you want to curl up in a huge lounge chair with a steaming mug of tea or coffee. Full of clues and not with action, it is an intelligent mind game between the criminal and the detective. One of the best descriptions of a cozy comes from www.cluelass.com, in which common elements include: “a domestic setting such as a country house or quiet neighborhood; a limited roster of suspects, all part of the victim’s social circle; little or no description of violence or sex; a mildly romantic subplot; and an amateur sleuth or eccentric professional.” Except for a murder (or other crime), there is very little violence and no gory details of the crime.
Classic authors: Agatha Christie, Ngaio Marsh, and Arthur Conan Doyle
Modern authors: Nancy Atherton, Donna Andrews, Julia Spencer-Fleming, Laurie R. King, and Aaron Elkins
My favorite cozy: Old Bones by Aaron Elkins
HARD-BOILED
Almost the exact opposite of a cozy is the hard-boiled sub-genre. Originally found in “pulp” detective magazines, this popular form of crime fiction surfaced in the 1920s-1940s. Common features: “a lone-wolf private detective, cynical yet quixotic; the mean streets of the inner city; characters from both the professional criminal class and the criminally rich; and liberal additions of violent action and disassociated sex.” (www.cluelass.com) But Raymond Chandler put it best: “[Hard-boiled] characters live in a world gone wrong…and the streets are dark with something more than night.”
Classic authors: Dashiell Hammett, James M. Cain, and Raymond Chandler
Modern authors: Dennis Lehane, James Lee Burke, Lawrence Block, and Charlie Huston
My favorite hard-boiled mystery: Gone, Baby, Gone by Dennis Lehane
POLICE PROCEDURALS
In police procedurals, the protagonist is usually a member of the police force who uses the forensic rules of evidence and departmental procedures to solve the crime.
Classic authors: Ed McBain, Joseph Wambaugh, Reginald Hill, and Ruth Rendell
Modern authors: Michael Connelly, Peter Robinson, T. Jefferson Parker, and Ian Rankin
My favorite police procedural: City of Bones by Michael Connelly
HISTORICAL
In historical mysteries, the crime occurs in the past rather than in contemporary times. The mystery is usually about a period of history prior to the life of the writer who wrote it. Even though their setting would now be considered historical, classic mysteries, such as Sherlock Holmes and Poirot (which were contemporary when written), are not considered part of the historical sub-genre.
Classic authors: Ellis Peters and Elizabeth Peters
Modern authors: Charles Todd, Rhys Bowen, Lindsey Davis, David Liss, and C.J. Sansom
My favorite historical mystery: River of Darkness by Rennie Airth
I mostly read hard-boiled detectives and police procedurals. So what sub-genre do you like the most?
The Mystery Bookshelf 
I have to admit that I’m what some people refer to as a “splash”-er: Sometimes Light and Sometimes Hard-Boiled. I still read light, humorous mysteries on occasion, but I have noticed that I’ve been reading fewer and fewer cozies within the past two years. Now my reading tends toward the police procedural and hard-boiled. Nor do I care about the time period. What catches my interest is the characterization, the plot and the setting. As long as those three ingredients keep me turning the page, I don’t particularly care in which sub-genre the book is.
i found your website as I was reading about how to write a mystery. I love police procedurals and hard boiled. But where do authors such as Patricia Cornwell and Sue Grafton fit in? I love those too. I like to read not so much how they solve the crime but the characters. How they battle what they have to do to survive their jobs and have a life. I love to read a mystery and feel like I know the characters.
thanks….Patti
Cornwell belongs to a subgenre of Police Procedurals called “forensic science,” but Sue Grafton’s character is more of a “hard-boiled” private detective.