A protest is an expression of objection, by words or by actions, to particular events, policies or situations. Protests can take many different forms, from individual statements to mass demonstrations. Protesters may organize a protest as a way of publicly making their The solid black flag is used to summon a driver to the pits. It is usually associated with a penalty imposed on the driver for disobeying the rules, but may also be used when a car is suffering a mechanical failure, leaking fluid, exhibiting damage such as loose bodywork, loose hood, dragging bumper, or any other damage that could potentially become a hazard to the driver or other competitors.

Opinions heard in an attempt to influence public opinion or government policy, or they may undertake direct action in an attempt to directly enact desired changes themselves

Periscope is an instrument used in submarines to observe activity above the water surface while the submarine is submerged. Periscope consists of an outer case with mirrors at each end set parallel to each other at a 45° angle. More complex periscope uses the prisms or advances fiber optics instead of mirrors.

DRDL stands for Defence Research and Development Laboratory.
It is a missile development laboratory located in Hyderabad, India.
DRDL functions under the Defence Research and Development Organisation (DRDO).
It is a premier system engineering laboratory focused on the design, development and delivery of various missile systems for the armed forces.
DRDL has designed and developed missile systems like the Prithvi and Agni series, Akash surface-to-air missiles, anti-tank missiles, torpedoes and countermeasures for tanks and aircraft.