What is integration? Calculus introduction

Integration (calculus) may be difficult to understand for some. There are two parts to it: definite integration which finds an area and indefinite integration which finds an antiderivative which is the opposite of differentiation. Here is my explanation of the concept in this video to help students, schools and college students with their maths.
The integral symbol is an elongated S. You don't need to understand infinitesimals or limits. You can calculate these with a CAS or computer algebra system for free.
I'd like to do more tutorials. I do like algebra for some reason.

[elipitchford]

I am a freshman in high school and I always find myself with extra time so I decided to learn more difficult concepts of math. The one thing that I never quite understood fully was integration. This almost 4 minute long video had cleared up a lot of stuff. Thank you so much.

[war]

having completed calculus somehow never understanding this, thank you for the extremely simple example.

[Abdulrahman-ukny]

short and to the point.
thanks for making the video.

[hyderali]

srsly really cleared my concepts too! thank you so much!

[pavankumarchellu]

I understood the concept but why do we take width as differential dx why not with some other notation.if we multiply the finite length with infinitesimal length we are getting differential area..why is it so....why not a finite area

[Kbgoda]

I'm sorry I still don't understand it..I understand it is the opposite of differentiation but how is it done?

[amritpalsingh]

Isnt that a square in the beginning.
delta x is width and for al the triangles it is equal.
height is different.

So

h1=3, h2=4, h3=4.

We are just squaring hs off.

meaning for rectangle with height h1, the deltax or width of that rectangle is 3 and likewise for other two rectangles.

[Hazellites]

So, the indefinite integral gives us the formula for the area under the curve, but the definite integral it gives us the formula and the exact area of the curve because it's limited from 3 to 6? For the indefinite part, what else is the formula useful for? Can it be used to solve different parts of the under a curve (By plugging in different numbers)? Or different parts of a function/graph? Is it indefinite because it's limits are (+ and -) infinity?