Where you put your vehicle on the road decides how much time and space you have when something goes wrong. In India the basic rule is simple: keep generally to the left, stay inside your marked lane, and move across only when you have checked, signalled and found a real gap.
The Motor Vehicles (Driving) Regulations, 2017 set out the duties: keep left unless signs, markings or a lawful manoeuvre require otherwise; heavy and slow vehicles keep to the left lane; change lanes only after signalling; never cross solid lines or painted islands. This section explains each duty and the practical habits that make it easy: choosing a lane early, keeping clear of the road edge, joining a highway from the acceleration lane and taking turns where lanes merge.
Start with Road Position: Keep Left Safely, then read Change Lanes & Merge Safely.