Tense – 1. a category of verbal inflection that serves chiefly to specify the time of the action or state expressed by the verb.

2. a set of such categories or constructions in a particular language.

3. the time, as past, present, or future, expressed by such a category.

4. such categories or constructions, or their meanings collectively.

Active Voice – the voice used to indicate that the grammatical subject of the verb is performing the action or causing the happening denoted by the verb; “‘The boy threw the ball’ uses the active voice”

16: Grammatical tense is a way languages express the time at which an event described by a sentence occurs. In English, this is a property of a verb form, and expresses only time-related information.

17: In grammar, the voice of a verb describes the relationship between the action (or state) that the verb expresses and the participants identified by its arguments (subject, object, etc.). When the subject is the agent or actor of the verb, the verb is in the active voice.

http://www.sil.org/linguistics/glossaryoflinguisticterms/WhatIsTense.htm

http://owl.english.purdue.edu/handouts/grammar/g_actpass.html