1G to 6G welding codes classify standard positions for groove welds, indicating workpiece orientation and weld complexity, from the easiest 1G (Flat) to the most difficult 6G (Fixed, 45-degree inclined pipe), testing skills in flat, horizontal, vertical, and overhead scenarios, with the 'G' signifying a groove weld and F for fillet (e.g., 1F, 2F). These positions assess a welder's ability to control the weld pool against gravity and are crucial for certification.