Depending on where you are from, different countries have different terms for "storm drain". abc

Subject to where you are from, different countries have different terms for "storm drain".
Accordingly to Wikipedia, a storm drain is actually a tunnel that carry runoffs (rain) from urban areas. For a layman, it helps to think along the line of sewage system operates beneath our cities.
In america, this is actually often called "storm drain" or "storm sewer".
In great britan, this is actually also known as "surface water drain" or "surface water sewer".
In Australia and New Zealand, it is often called "stormwater drain".
And there you have it, next time you hear someone mentioning "storm drain", "storm sewer", "surface water drain","surface water sewer" and "stormwater drain", congratulations, you know they mean the exact same thing.
Functions of storm drain include draining excess water (rain or storm water) and ground water from pavement, streets and carparks into rivers and streams to protect yourself from flooding.
Although storm drains perform a amazing job of draining excess water from the urban areas, the inlets are essentially openings where left uncovered can pose a hazard to pedestrians. Left uncovered, rubbish will enter the storm drains and cause choking which might eventually end up with flooding.
To guarantee storm drains serve their purposes while minimizing the risks posed to pedestrians and to prevent choking of the drains, drain covers (gratings) are used to cover the inlets (openings) of the storm drains to achieve two purposes.
Over at Jonite, we specialise in steel reinforced drain covers ( gratings ) which cover your storm drains while preserving the aesthetic aspects of the architecture around the drain covers.