This Special Issue aims to provide a platform for researchers to share their latest advances in neural networks, deep learning, and the correlation between machine learning and symmetry as well as their applications to solving real-world problems. Topics of interest include, but are not limited to, image recognition, speech recognition, natural language processing, recommendation systems, classification, prediction, etc. Submissions will undergo a rigorous peer-review process, and accepted papers will be published in this Special Issue of Symmetry.