The Learning Systems Group at Caltech studies the theory and applications of Machine Learning (ML). The theory of ML uses mathematical and statistical tools to estimate the information (data and hints) needed to learn a given task. The applications are very diverse and continue to expand to every corner of science and technology. The group works on medical applications of ML, on e-commerce and profiling applications, and on computational finance, among other domains. These applications use the latest techniques of neural networks and other models, and often give rise to novel ML theory and algorithms. Our latest projects are data-driven approach to predicting the spread of COVID-19 in every U.S. county, and ML approach to medical diagnostics using low-resolution ultrasound.