Without covering all the kinds of narcotics crimes out there, which get specific down to the type of controlled substance, to the amount found or possessed, it is easier to look at the character of the offense; Possession, Sales, Transportation, and Manufacturing.
As with all controlled substances, possession alone can be enough to be arrested and charged. This would subject you to felony arrest, bail, and charges.
Transportation includes an extra element or two depending on whether you have been charged with simple sales or sales/transport.
For example, under Health and Safety Code Section 11360 you must, 1) unlawfully give away/transport a controlled substance, 2) that you knew of its presence, 3) you knew the nature of that substance, 4) that substance was marijuana, and 5) the amount you possessed was more than 28.5 grams.
Therefore, the state would have to prove that the amount was more than what's considered personal use and there must have been an action taken that would indicate a 'handing over' to another person.
To be arrested or charged with Sales, you must have, 1) possessed the substance, 2) you knew of its presence, 3) knew the nature of the substance, 4) when you possessed it you intended to sell it, 5) the substance was marijuana, and 6) it was a usable amount.