This January, PyTorch celebrated its 5 year anniversary! I reflected on what it meant to me in this tweet thread, and this conversation with my colleagues Mike Schroepfer, Lin Qiao, and Yann LeCun. When we started PyTorch development in 2016, it was a collective effort by a band of people from the [Lua]Torch community with a big chunk of people and funding from Meta and individuals contributing from NVIDIA, Twitter and other entities.