Explanation
Expresses a continuing action or a resulting state; 'is ~ing', 'has been', 'has'.
Formation
Verb-て form + いる
Detailed explanation
The ～ている grammar point is used to describe a continuing or repeated action, or the result/state of a completed action. Depending on the context, it can be translated as 'is ~ing', 'has been ~ed', or simply 'has/are/is'. In passive contexts (e.g., 食べられている, 開けられている), it shows that something has been done and remains in that state. With intransitive or non-passive verbs, it shows an ongoing or resultant state (e.g., 寝込んでいる, 終わっている).
Examples
Mado ga akerarete iru.
The window is open (someone opened it and it remains open).
Keeki ga zenbu taberarete iru.
The whole cake has been eaten.
Kanojo wa byouki de nekonde iru.
She is bedridden due to illness.
Shukudai ga owatte iru.
The homework is finished (has been done).
Practice
Grammar content sourced from hanabira.org.