Lines and symbols on the road are meant to show the alignment of the roads. Ideally these are reflective so that you may clearly and safely follow the roads even at night.
According to highwaycode.com, a site dedicated to enlightening drivers and other road users about safety, road markings indicate the number of lanes on the road, where you may overtake other vehicles, which lane to use for turning, and where you must stop for signs or other traffic signals.
Road markings are basically of four major types centre lines, edge lines, cross walks and pavement messages.
Centre lines
These are lines in the centre of the road to separate traffic proceeding in opposite directions.
Broken lines are used in areas where there are no restrictions on overtaking, a solid line is painted alongside the broken line.
You may not overtake if the solid line is on your side of the centre line.
Overtaking for traffic in both directions is strictly forbidden where the centre is marked by double solid lines.
Do not overtake unless you can see the road ahead is clear.
Edge lines
These are solid lines along the side of the road. They indicate where the edge is and can be used also as traffic guidance.
An edge line which slants towards the centre of the road forewarns that the road is narrow ahead.
An edge line may be crossed only by traffic moving to and from the shoulder of the road.
Cross walk
White solid lines across the road are usually used to denote pedestrian’s crosswalks commonly at intersections. You must stop for pedestrians at cross walks.
A solid white line across the road, usually at intersection, show where you must stop for a GIVE WAY sign, STOP sign or for red traffic light signal.
Pavement messages
These are messages or symbols which are lettered or painted on the roads pavement to warn of conditions ahead.