Finding out what time it is, is often as simple as looking at a clock. But when you need to know the time on another place on Earth, you also need to know in which timezone you are in. Timezones are a bit more complicated than the UTC-offset, or a timezone abbreviation (such as GMT or EST). In order to correctly identify a set of Daylight Saving Time rules (and other changes in UTC-offset) for a specific location you need to know its Timezone Identifier. These have the form of Europe/London or America/India/Knox and any decent sysadm (and hopefully every developer!) will know what the Timezone Identifier for their specific area is. It becomes more difficult if you need to know the Timezone Identifier in a unfamiliar location, such as Indiana in the US, where there are eleven different identifiers.