SSL uses a small portion of labeled data and lots of unlabeled data to train a classification model. There are several methods to label the portion of unlabeled data to be used as a training set e.g. Pseudo-labeling.
https://blog.roboflow.com/what-is-semi-supervised-learning/#:~:text=Semi%2Dsupervised%20learning%20(SSL),supervised%20learning%20and%20unsupervised%20learning.
