Standard Time refers to the uniform time system used across different regions to coordinate activities and schedules. It was established to replace the varied local times that were based on the position of the sun. The world is divided into time zones, each typically one hour apart, allowing for a consistent way to measure time. The concept of Standard Time was popularized in the late 19th century, largely due to the expansion of the railroad system. Sir Sandford Fleming proposed dividing the world into 24 time zones, which led to the adoption of Greenwich Mean Time (GMT) as a reference point for coordinating time globally.