According to Google documentation, UGC includes:
Customer reviews are the most accessible and popular option for commercial sites, users can leave them through a special form.
Overviews are real stories of use and the most powerful UGC tool for business. A quality review can increase sales many times over. It is customary to offer a reward for reviews - then real users are willing to write them.
Forum messages - on thematic forums, people can ask for advice or share their opinions, users are willing to write such messages.
Comments - demonstrate interest in the topic or product.
Images are posts on social networks and on review sites with photos of the product, as well as photos in reviews and comments on the site.
Videos are content that is more suitable for social networks, but it is difficult to obtain - additional stimulation of users is needed, since its creation requires effort.
Votes, likes, hearts - reactions convince visitors of the value of information and increase trust.
The most common types of user-generated content are related to social networks and are generated there, but there are also those that can be successfully applied on a website: these are reviews, overviews, photos and videos, as well as your own forum.