Hello there,
YouTube is an American online video sharing platform. You can find many educational videos there, which may help you to prepare for your exam. YouTube is an in-built application, so you do not have to install it in your phone. There are videos related to everything such as education, cooking, music, pet videos, gaming, vlogs, and so on. You can directly search the topic you want to watch, and a list of videos occur. You can click on any of them, and start watching. For example, there are teachers who upload their videos,and they explain very nicely. You can take help from them. You can even like, share, comment or upload your own videos there.
Hope this answer helps you.
Good luck!!

Hey!

YouTubeis a video sharing service where users can watch, like, share, comment and upload their own videos. The video service can be accessed on PCs, laptops, tablets and via mobile phones.

Usually it is in our smart phone ,you just click on the you tube it works but if you findYouTubenot working, simply press and hold the power button on your device, and tap the restart option that appears on the screen. After the smartphone turns back on, open theYouTubeapp and check if the problem has been solved.

Hope you find this informative

Good luck