SMT (Surface Mount Technology) is the automated manufacturing process for attaching electronic components directly onto a PCB's surface. It involves solder paste printing, precise component placement, and reflow soldering. Key advantages include miniaturization, high-speed assembly, and improved performance. SMD (Surface Mount Device) refers to the components themselves designed for this process. Characterized by small size, flat leads (gull-wing, J-lead), or solder balls (BGA), SMDs include resistors, capacitors, ICs, and more. The core difference is that SMT is the method (how components are mounted), while SMDs are the parts (what is mounted). SMT enables the use of SMDs. Together, they dominate modern electronics manufacturing, enabling the compact, powerful devices found in smartphones, computers, automotive systems, medical equipment, and virtually all modern electronics. SMT is the technology; SMDs are the devices assembled by it.