In physics, dimensions refer to the fundamental aspects or parameters that characterize different aspects of the physical universe. These dimensions are used to describe and measure quantities such as length, mass, time, and electric charge. The choice of fundamental dimensions is somewhat arbitrary and depends on the system of units being used.

A derived physical quantity can be expressed in terms of some combination of seven basic or fundamental quantities. For convenience, the basic quantities are represented by symbols as ‘L’ for length, ‘M’ for mass, ‘T’ for time, ‘K’ For temperature, ‘I’ for current, ‘C’ for luminous intensity and ‘mol’ for amount of mass.

The dimensions of a physical quantity are the powers to which the concerned fundamental units must be raised in order to obtain the unit of the given physical quantity.

When we represent any derived quantity with appropriate powers of symbols of the fundamental quantities, then such an expression is called dimensional formula. This dimensional formula is expressed by square bracket and no comma is written in between any of the symbols.