Maxwell's Equations:

"The most important equations of all time."
"In every branch of knowledge the progress is proportional to the amount of facts on which to build, & therefore to the facility of obtaining data."
James Clerk Maxwell
James Clerk Maxwell (1831 - 1879) was a theoretical Physicist & famous Mathematician; who took a set of known experimental laws (Faraday's Laws, Ampere's Law) & unified them into a symmetric set of equations known as Maxwell's Equation - that explains the properties of magnetic & electric field.

Maxwell was one of the first to determine the speed of propagation of electromagnetic (EM) waves was same as the speed of light. And hence he conclude that electromagnetic (EM) waves & visible light were really the same thing.

If you need to testament to the  power of Maxwell's Equations, look around you - radio, television, radar, wireless internet access & Bluetooth technology. These are the few examples of contemporary technology rooted in electromagnetic field theory - Maxwell's Equations.
Maxwell's Equations are four of the most influential equations in Physics : 
M1. Gauss's Law for Electric Fields: 
M2. Gauss's Law for Magnetic Fields: 
M3. Faraday's Law: 
M4. Ampere - Maxwell Law: