There's a broad range of driving offences, but they mainly fall under two categories: dangerous driving, and careless or inconsiderate driving.
The offence of dangerous driving is when driving falls far below the minimum standard expected of a competent and careful driver, and includes behaviour that could potentially endanger yourself or other drivers.
Examples of dangerous driving are:
speeding, racing, or driving aggressively
ignoring traffic lights, road signs or warnings from passengers
driving under the influence of drink or drugs, including prescription drugs
driving when unfit, including having an injury, being unable to see clearly, not taking prescribed drugs, or being sleepy
knowing the vehicle has a dangerous fault or an unsafe load
Distractions are also causes of dangerous driving, for example:
using a hand-held phone or other equipment
reading, or looking at a map
talking to and looking at a passenger
lighting a cigarette, selecting music, tuning the radio
Careless or inconsiderate driving
The offence of driving without due care and attention (careless driving) is committed when your driving falls below the minimum standard expected of a competent and careful driver, and includes driving without reasonable consideration for other road users.
Some examples of careless or inconsiderate driving are:
overtaking on the inside
driving too close to another vehicle
driving through a red light by mistake
turning into the path of another vehicle
the driver being avoidably distracted by tuning the radio, lighting a cigarette etc
flashing lights to force other drivers to give way
misusing lanes to gain advantage over other drivers
unnecessarily staying in an overtaking lane
unnecessarily slow driving or braking
dazzling other drivers with un-dipped headlights
Driving under the influence
Driving whilst under the influence of alcohol or drugs (legal and illegal) is a specific offence, but can also be considered as dangerous or careless driving.