YouTube Go is a free, official app from Google that's designed for mobile devices, in particular those that are on mobile networks. It's especially useful in areas with older 2G or 3G networks. It provides a variety of features that make the YouTube more bandwidth-conscious and help avoid buffering while on the go.
Flexibility of features
The biggest draw of YouTube Go is that it allows you to watch videos even when you're saving data, or when you're in a region (or country) that doesn't provide fast downloading of data. Even if you're on a 2G network in India, as Google's examples go, the app is designed to make it all feasible. You can set a size cap (in megabytes) for videos you watch, limiting the bandwidth and data they consume. Besides that, the app has most of YouTube's existing features, such as comment discussions and recommendations.
Handy, wherever you are
Essentially, YouTube Go provides features that are useful whether or not you frequently use data. Even if you only occasionally watch videos without wi-fi, and live in an Internet-heavy region, the fact it integrates standard YouTube features such as recommendations make the app great to use. If you spend any data at all watching videos on YouTube, then give YouTube Go a try.