This became increasingly awkward as railways र telecommunications improved, because clocks differed between places by an amount corresponding to the difference in their geographical longitude, which was usually not a convenient number. This problem could be solved by synchronizing the clocks in all localities, but then in many places the local time would differ markedly from the solar time to which people are accustomed. Time zones are thus a compromise, relaxing the complex geographic dependence while still allowing local time to approximate the mean solar time. There has been a general trend to push the boundaries of time zones further west of their designated meridians in order to create a permanent daylight saving time effect. The increase in worldwide communication has further increased the need for interacting parties to communicate mutually comprehensible time references to one another.