please explain the concept of calculus, differentiation and integration?

In calculus, we deal with the way a function behaves when we find its rate of change with repect to a variable (in differentiation) and when we find the area under its curve (integration)

 

Differentiation:  suppose we have f, a function of x. Then the amount by which f changes with a very small change in x (denoted by dx) depends on the position at which it is considered. Sometimes f may vary slowly or sometimes faster. Thus its rate is called differentiation with respect to x.

It is denoted by df/dx

 

Integration: If i want to find the area under the curve f between f and x axis, i make rectangles (using the rectangle method you might have read to find the area graphically) but it has a lot of error included in it. That error decreases as i decreaes the with of the rectangle. As the with becomes infinitsemally small, we call it integration with repect to x.