There are Several Online Platforms to learn Data Science.But for those who are looking to learn Data Science for free YouTube is the best platform.I strongly recommend to follow these channels if you are heading towards Data Science.

The Channels that I mentioned here also contains mathematics channels because it is also a part of Data science.
("Below Red Coloured words are Links to channels")

1. CodeBasics
This Channel has all playlists that are required for data science.He also included some real world data science projects.The way he teaches is very interactive. Even if you are noob at programming he has python playlist from scratch.

2. DataSchool
If you  want to understand functionality behind the library functions,what they will do and how do they work then this channel is a very good choice.

3. Data Professor
If you are completely from a non technical background then this channel is for you.

4. Ken Jee
This channel mainly focuses on real world data science projects

5. Sentdex

Best channel to learn Data Science in depth.It includes almost all stuff that you can do with python

6.Cory Schafer
Best for learning Python Libraries
7.Andreas Kretz

Building up big data platforms. Figuring out how to ingest, process and store data. Enabling Data Scientists to do awesome stuff for customers .That's what data engineering, the plumbing of data science is all about. This channel  help you get into this awesome job.

8.StatQuest with Josh Starmer

StatQuest breaks down complicated Statistics and Machine Learning methods into small, bite-sized pieces that are easy to understand. 

 
9.Krish Naik
He is  self motivated to learn data science.He explains the concepts very clearly so that a beginner can easily understand.

10.3Blue1Brown

All tutorials are made in animated format so that we can understand even much better .This channel contain mathematics vedeos that make math at your finger tips,you will definitely love math if you watch these vedoes and also it is best channel to learn Neural networks,Deep Learning.

.11. Python Programmer

12. Lex Fridman

13.Abhishek_Thakur

14. RichardOnData

15.Data Science Dojo

Do Share Some of your best Channels that you found.