What's dark matter? What is dark energy?

Kindly refer to the links given below to get your answer : 
https://www.meritnation.com/ask-answer/question/what-is-dark-matter-how-does-it-helps-in-the-study-of-expan/science/5630738


https://www.meritnation.com/ask-answer/question/what-is-dark-energy-and-what-its-work/science/6770377