what is time domain and frequency domain.And in which way they differ.explain basically..i am new to this one.

Look back to the definition of a function of a single variable. The independent variable belongs to a "domain". The "domain" of a function is described as set of numbers eg. "the set of positive real numbers", or the "real numbers in the closed interval from -1 to +1". The dependent variable is referred to as the "range", and it can also be described as a set of numbers. Given that information what do you think "time domain" and "frequency domain" refer to?

Although Papabravo's answer is immaculate,I think you may be looking for a more "Popular Science" level of answer. If you look at a waveform with an Oscilloscope,it shows you how the signal varies over time. The horizontal axis of the display is in units of time.("time domain") This cannot easily tell you everything about many waveforms,which are made up of a combination of several,(or more) frequencies. A Spectrum Analyser shows the spectral makeup of the signal. The horizontal axis of the display is in units of frequency. ("frequency domain") I hope that you want to know this to help you understand the concepts--not as a ready made answer to an exam question.

A good and illustrative explanation from vk6zgo. Perhaps one should add that the formal (theoretical, mathematical) relationship between both domains is performed by the well-known Laplace transformation.