Important Notes for All Vanced Manager Users:

Vanced Manager will directly mounts vanced on top of Youtube in the /data/app directory, making it easier and faster than before.
YouTube Vanced will not block ads while casting since when you use the casting feature, it doesn't send the video from your phone to the Chromecast/TV. Instead, your phone acts like a remote controller for the YouTube app in your Chromecast/TV. That is why the advertisement is displayed.
Purchasing items in the non-root version of the app will not work as microG doesn't support it. Hence, it is preferable to use the original YouTube app or using the web version for any purchase.
If your videos are lagging or the application starts to crash while watching live videos, please enable VP9 codec from codec override present under vanced settings. Google forced the ExoPlayer v2, which is highly experimental and unstable on unsupported devices.
YouTube has dropped support for Android 5 (Lollipop) with v17.xx.xx. Hence, the minimum supported version is now Android 6 and above.

Watch YouTube in Vanced Tube Experience

Features the option of an AMOLED black theme to reduce eye and battery strain.
It blocks All videos ads and allows you to play videos in the background or in Picture in Picture (only on android 8.0 and up)
Your favorite channels can be allow listed from both video ads and SponsorBlock if you wish.
Swipe controls allow you to control brightness and volume like how it is in other video player apps such as VLC or MX Player (with configurable padding).
A new auto-repeat feature allows you to enjoy videos like TikTok's/vines or continue playing a song on loop.
Not like the recent comments section or mini player. Those can also be toggled to the tablet versions, which are remarkably like the previous version (albeit slightly buggy).

Customize Your Way for Watching YouTube

Allows you to override Codec options such as forcing H264 for old devices or VP9. This also allows you to force HDR playback or turn off 60fps if you prefer a cinematic experience.
(Custom device configs for these features can be found on Vanced Team discord or XDA)
Force the default video resolution as high or low as you want and even override your screen resolution for that sharp 4k playback on any device and allows you to change the default playback speed to anywhere between 0.25x to 2x (assuming your device is powerful enough)
Allows you to toggle home ads, most UI ads, Merchandise ads, Community posts, Movie upselling, compact banner info (such as the covid info), remove comments entirely, tight movie, movie shelf removal, and many more!

SponsorBlock - Skip Sponsor Segments in YouTube Videos

Features the ability to skip annoying sponsor segments (where a YouTuber advertises a service or product in the middle of a video)
It also supports skipping other categories, such as intros, outros, and reminders to subscribe.
It uses the API found here. You can find more information on how it works.
It also allows you to submit your segments to the API and contribute to the broader community.
Complete control over whether to automatically skip a segment category, show a button for skipping, or not skip it.
Highlights the segment in the specific color based on its category in the playback timeline.

Take control of YouTube and return YouTube Dislike

Reverses Google's removal of the dislike counter so you can finally see the quality of videos again
It uses the Return YouTube™ Dislike API found here. Find more information on how it works.
It uses extension\vanced userbase dislike submissions as a sample group to estimate total dislike counts on new videos and archived data for old videos.

Non-Root nstallation tips:

Download Vanced Manager Android, install it.
Open Vanced Manager and tap the blue arrow in the lower right corner.
Begin installing Vanced microG. (Without which you won't be able to install Vanced (or Music Vanced) or use login)
Then install Vanced (or Music Vanced), log in to your account and enjoy!

For Root User:
Install Vanced Manager
Open Vanced Manager and tap on the "Magisk" icon to grant root permissions.​
Once you are in, begin installing Vanced (or Music Vanced).​

// Option A //

To download Vanced Manager mod from HappyMod.com.
You need enable the option "Unknown Sources".
1. Click on the above link to download Vanced Manager mod APK.
2. Save the file in your device Downloads folder.
3. Now tap on Install and wait for the installation to finish.
4. Once it is done, open the game and start playing it right away.

// Option B //

To download Vanced Manager from HappyMod APP, you can follow this:
1. Open your browser and download the HappyMod APK file from HappyMod.com - the only official website of HappyMod.
2. Open Android Settings and go into Privacy or Security.
3. Tap the option to Allow Unknown Sources and enable it.
4. Go to your Android downloads and tap the APK file.
5. Follow the directions on the screen to install it.
6. Search Vanced Manager in HappyMod App.