Standard time is useful due to the following reasons: 1) Local time can lead to confusion if all countries and regions use their own local time. 2) Airways, railways and other transport and communication means would be disrupted without standard time. 3) Following an international agreement, Greenwich Mean Time can be linked with the local time of the standard meridian. This makes it easier to determine the exact time in regions around the world because of the fixed points such as the international dateline and Greenwich meantime.