Simple possession of marijuana (cannabis) less than 20 grams is a first-degree misdemeanor, punishable by a maximum of 1 year in jail.
Possession of marijuana over 20 grams but less than 25 pounds may be charged with felony possession of marijuana, or possession of cannabis greater than 20 grams. This charge is a 3rd degree felony, punishable by a maximum of 5 years in prison.
Felony possession charges can be reduced to misdemeanor charges if it can be shown that the police did not properly weigh the suspect cannabis. If the cannabis is weighed with its packaging material (such as a case or plastic baggie), then the weight will likely be greater than 20 grams. Sometimes cops do this just so they can arrest you for a felony and not a misdemeanor.
Over 25 pounds will be considered trafficking in marijuana.
Felony possession is not the same thing as possession with intent to sell. In order to charge a person with possession with intent to sell, there must be some indicia of sales or intent to sell the marijuana. This may include large amounts of cash, whether the marijuana has been individually packaged, and whether the marijuana is found along with a scale and plastic baggies.