As the name suggests Advance Tax is basically the tax you pay in advance on the basis of your assessed income. For example I expect to earn 10 lakh in current financial year then I pay tax on this estimated income.
An interesting thought occurred to me recently, Can you think without words?? Almost all of our thinking is done in words and what if someone does not know any language, how would he think (if at all!!) I guess in that case mental processing will be done in form of images (imagination). Infact there is experimental data suggesting it. (I am applying for next years nobel prize!)