Screw piles are deep foundations consisting of helical plates welded to a hollow steel pipe. They can be installed rapidly using a turning motion and bear loads immediately. This document discusses screw pile geometry, installation, uses, design methods, and failure models. It presents two approaches for predicting axial capacity: the LCPC method relates cone penetration tests to capacity, while empirical torque correlations measure installation torque. Both methods provide good predictions in soils like sand and clay but not glacial till. The document concludes screw piles are advantageous foundations but lack acceptance and understanding in some engineering communities.