The Kind of Action:
The present tense primarily expresses linear action; however, depending on context can focus on a point in time. With the Greek verb the time is secondary to the type of action; therefore, the present tense is not restricted to only expressing action going on in the present time. The time element is expressed by the mode more than the tense; however, the progressive force of the present tense needs to be considered regardless of what mode it is used with, especially the Subjunctive and Optative modes.
The Aoristic Present
Denotes point-in-time action in the present time; taking place at the moment of speaking or writing without reference to its progress.
The Gnomic Present
Represents that which is assumed to be true at all times; simply affirming that something does happen under given circumstances.
The Historical Present
Presents a past action as though it were going on at the moment it was written. It expresses vividness in dramatic narration where the writer can still picture the events in his mind as though they were still happening and he is still involved in them.
The Futuristic Present
Pictures a future event, which is so certain to the writer that he writes of it as though it was already taking place.
The Descriptive Present
Represents an action now in progress; it is going on now. This is the most frequent use of the present tense and is the closest to the root idea.
The Progressive Present
The action or state began in the past and is still in progress at the present. Usually has an adverb of time.
The Iterative Present
The action is repeated at successive intervals or in consecutive periods.
The Customary Present
The action habitually occurs, or it may be reasonably expected to occur; it is something that usually occurs.
The Periphrastic Present
This use adds emphasis to the linear aspect of the present tense by means of a present participle.
The Tendential Present
The action is purposed or attempted, but is not actually taking place. It may or may not have been attempted, but it tends towards an attempt.
The Conative Present
The action has begun or been attempted, but it is not now in progress, having been interrupted.
The Inchoative Present
The action is just beginning at the present time, without any emphasis on the progress of the action. The emphasis is on the beginning of the action.
The Perfective Present
This use refers to a fact which has come to be in the past emphasizing the continuation of the existing results as a present reality. The results are seen as going through the present time.