The modes of metal transfer describe how filler metal is transferred across the arc and into the weld puddle, with each mode carrying distinct requirements, advantages, and limitations. This article introduces the four basic modes of GMAW metal transfer and focuses specifically on short circuit transfer, explaining how it works and why it produces low heat input. While short circuit transfer is well suited for thin materials, gaps, and all-position welding, it is highly susceptible to lack of fusion on thicker sections. The article demonstrates how visually acceptable welds made with short circuit transfer can mask serious internal defects when used improperly. Understanding these limitations is critical to selecting the correct transfer mode and ensuring weld quality, especially in structural applications governed by AWS codes.