Welding is a conventional joining process that has followed the recent developments in other manufacturing processes, continuing to be an extremely used and investigated process. Several technologies developed in other areas of knowledge have converged in the area of welding, allowing significant improvements in the quality of the products obtained and in the increased productivity of the processes. Although some techniques have been implemented and studied for several decades, the interest of researchers in welding has not diminished, as it can be seen through new processes that have emerged, such as Friction Stir Welding, in addition to many other notable developments in welding processes which apparently seemed to have reached their final stage of maturity. This work brings together a set of very interesting works, being a living proof that welding continues to be heavily investigated and that the developments around this manufacturing process are constantly emerging. Because the materials continue to evolve and the technology around welding also continues to develop at a very good pace, studies on the weldability of new materials and the application of new techniques and technologies to already well known welding processes does not stops happening. The editors are proud to have collected this set of works that can help scholars and researchers to broaden their knowledge in the field of welding, thus contributing to the creation of a knowledge base that allows researchers to start new investigations and achievements in the coming decades.