What Genres Are There?

From Manga Updates:

Action
A work typically depicting fighting, violence, chaos, and fast paced motion.

Adventure
If a character in the story goes on a trip or along that line, your best bet is that it is an adventure manga. Otherwise, it's up to your personal prejudice on this case.

Comedy
A dramatic work that is light and often humorous or satirical in tone and that usually contains a happy resolution of the thematic conflict.

Drama
A work meant to bring on an emotional response, such as instilling sadness or tension.

Fantasy
Anything that involves, but not limited to, magic, dream world, and fairy tales.

Gender Bender
Girls dressing up as guys, guys dressing up as girls.. Guys turning into girls, girls turning into guys.. I think you get the picture.

Harem
A series involving one male character and many female characters (usually attracted to the male character). A Reverse Harem is when the genders are reversed.

Historical
Having to do with old or ancient times.

Horror
A painful emotion of fear, dread, and abhorrence; a shuddering with terror and detestation; the feeling inspired by something frightful and shocking.

Martial Arts
As the name suggests, anything martial arts related. Any of several arts of combat or self-defense, such as aikido, karate, judo, or tae kwon do, kendo, fencing, and so on and so forth.

Mecha
A work involving and usually concentrating on all types of large robotic machines.

Mystery
Usually an unexplained event occurs, and the main protagonist attempts to find out what caused it.

Psychological
Usually deals with the philosophy of a state of mind, in most cases detailing abnormal psychology.

Romance
Any love related story. We will define love as between man and woman in this case. Other than that, it is up to your own imagination of what love is.

School Life
Having a major setting of the story deal with some type of school.

Sci-fi
Short for science fiction, these works involve twists on technology and other science related phenomena which are contrary or stretches of the modern day scientific world.

Shounen
A work intended and primarily written for males. These works usually involve fighting and/or violence. (Note: Some works can be both Shoujo and Shounen)

Slice of Life
As the name suggests, this genre represents day-to-day tribulations of one/many character(s). These challenges/events could technically happen in real life and are often -if not all the time- set in the present timeline in a world that mirrors our own.

Sports
As the name suggests, anything sports related. Baseball, basketball, hockey, soccer, golf, and racing just to name a few.

Supernatural
Usually entails amazing and unexplained powers or events which defy the laws of physics.

Tragedy
Contains events resulting in great loss and misfortune.

*Note: Certain Genres Have Been Omitted Due to Wikia Guidelines*