Japanese/Grammar/～ている

The ～ている form has several uses.
 * Progressive
 * Completed actions
 * Stative
 * Habitual
 * Incomplete actions

Conjugation
While Japanese grammar doesn't always correspond to what we know from English, they both use auxiliary verbs in many circumstances.

Continuous tenses in English use the auxiliary verbs am, are, is, was and were.

The Japanese language has a similar auxiliary verb いる with the ～て form of the verb.

Continuous actions
When speaking of continuous actions that occur in the present or occurred in the past, the form has the same meaning as the English continuous tense.

Incomplete tasks
When いる is used in the present-negative conjugation, it conveys a sense of action not taken.

Habitual
This form may also be used to describe a habitual activity.

Stative vs Non-stative verbs
Much like English, there are verbs that describe a state of the subject, rather than an action. These type of verbs are called stative verbs. You may want to think of these as actions that started in the past, arrived to a state, and this state persists to the present.

くる, いく, and かえる
When the verbs くる, いく, and かえる are used in the ～て in conjunction with the auxiliary verb いる, they are translated as has come, has gone, and has returned, respectively.

Exceptions
There are some irregular cases with this form.


 * 1) You can use the word 知っています, but not 知っていません.  Instead, you'll use the negative form of masu - 知りません.
 * 2) You also can't use ある, いる, and 要る in the ～ている form at all.  The same can be said with potential forms of verbs (e.g., 話せる).

Colloquial Variations
When speaking at a high speed, sometimes syllables are dropped from words to make them easier to say. Colloquial variations of the continuous forms exist and are recognized in the Japanese language. While they are not used in proper writing, these forms are used in every day conversation, especially among friends and family.

All the sentences mean "I am riding the train." Notice that the two sentences on the right have simply dropped the い　from いる／います. By dropping the い, the sentence becomes easier to say quickly. This is a standard colloquial form of the continuous tense, and it works with the non-past continuous and the past continuous. The above example is the present continuous, so let's see an example of the past continuous:

Once again, the い was dropped, which forms the colloquial variation. Just remember to use the standard form when writing, but when speaking, the colloquial version will be OK when speaking among friends. However, when speaking to someone of higher status, you may wish to use the standard polite form.