The following are great sites that I personally recommend to learn from. You can click on the images to be linked to the site.

Image result for pbs infinite series
This is a fairly new YouTube channel by PBS very similar to NumberPhile but distinct enough to deserve the recognition I hope to give it. Not only does it discuss and touch on fascinating and complex topics in mathematics in very simple terms, but the channel also uses rigorous proof when explaining. Unlike other channels that leave out the complex bits of a concept so as to not confuse an uninformed viewer, this channel takes the leap to do so and still makes it digestible to a very wide audience. Highly recommended.
Image result for pbs space time
Another fairly new Youtube Channel by PBS that is focused more around math than physics. It has all the great qualities aforementioned in PBS infinite series although this one does leave out the very rigorous proofs because it is simply not possible to do so otherwise. I admit, even I get bored listening to it but if you fight through, there is some great content being shared and amazing insights. I recommend the Feynmann’s Infinite Paths video.
An interesting site completely devoted to time. They discuss mathematical, physical, and philosophical interpretations both modern and historically. Various experiments as well as proposed time travel devices are mentioned. Altogether, a very fun site.
Mandel Bulb is an amazing site that consists of the work of various artists who make works out of 3D fractals. The work above is a real mathematical fractal. Check out some of their other works.
MinuteLabs is a site filled with fun simulations, interactive graphics, and other nice things to just experiment with and look at.
A collection of pages called “Cantor’s attic” covers information about all types of infinity, large numbers, and other crazy topics in transfinite set theory. It is still in development but provides an amazing and vast collection of various types of ordinals and cardinals and concepts about axioms and such.
A blog called “Quantum Diaries” written by physicists through international collaboration which explains various phenomena in particle physics, quantum mechanics, and some cosmology.
space fil
A YouTube Channel called “3Blue1Brown” that teaches really complex and interesting math through elegant visualizations.
A YouTube channel called “NumberPhile” where an immense amount of interesting concepts in mathematics is explained in very simple ways.