What is modern civilization??

Try wikipedia

Wiki' is a good place to start, keeping in mind that it is not completely reliable. It's a bit of a judgement call as to what is considered modern civilization because different authorities may have different views about what is "modern", or what facets of civilization are good markers for defining "modern". In short, don't expect one definitive answer.

Is this an essay question? If so, look up a few sources as to how they define modern civilization, then using their arguments come to your own definition of modern civilization. Don't fret about getting it 'wrong' or 'right'. What's more important is how well you developed your own opinion and how well you can back this up.

You cannot ask any of us to tell you what modern civilization is, because it is so vague that there is likely no set definition between us. Therefore, it is important for you to come to your own conclusion. If you want, try looking it up in a dictionary or wikipedia for a solid base to build your argument.