In Zabbix, templates play a major role in simplifying the configuration and allowing large scale changes. If you are a proficient user of word processors, you probably use styles. The same concept is used in TeX, CSS styles for the web and elsewhere separating content from the presentation helps to reduce amount of work required when changes have to be made.
While the comparison to styles might seem far-fetched at first, it actually is similar enough. Just like styles, you can separate a host from the services you provide, and you can define these services in a centralized fashion. Same as with a word processor document having heading style that allows to change font size for all headings of that level with one action, templates in Zabbix allow to change some parameter for all linked in hosts, direct or nested.
As we saw with all the rearrangement of items and triggers in templates, it is easier to plan a sane template policy before getting to the actual configuration. It is strongly...