Editing Esperanto grammar (section)

===Copula===
The verb ''esti'' (to be) is both the [[copula (linguistics)|copula]] ("X is Y") and the existential ("there is") verb. As a copula linking two [[noun phrase]]s, it causes neither to take the accusative case. Therefore, unlike the situation with other verbs, word order with ''esti'' can be semantically important: compare ''hundoj estas personoj'' (dogs are people) and ''personoj estas hundoj'' (people are dogs).

Existential verbs do not use [[dummy pronoun]]s. Thus, the phrase ''estas pomo'' (there is an apple) does not contain a leading pronoun, as does its English translation.

One sometimes sees ''esti''-plus-adjective rendered as a verb: ''la ĉielo estas blua'' as ''la ĉielo bluas'' (the sky is blue). This is a stylistic rather than grammatical change in the language, as the more economical verbal forms were always found in poetry.<ref>However, the reverse – changing verbs to adjectives – does not behave in the same way: ''Morti'' (to die) does not have the same meaning as ''esti morta'' (to be dead).</ref>