Tenses & Moods in Sanskrit

There are 6 tenses & 4 moods in Sanskrit. The following shloka enlists all forms of verbs corresponding to tenses & moods in Sanskrit.

लड्वर्तमाने लेड्वेदे भूते लुङ्लङ्लिट्स्तथा |

विध्याशिषोस्तु लिङ्लोटौ ऌङ्ऌटौ लुड् भविष्यति ||

A time line plot of the same (verb to tense/mood mapping) is shown below.

Timeline Based Categorisation of Tenses In Sanskrit

The whole timeline has sections past ( भूत ) and future ( भविष्य ) tense with present ( वर्तमान ) tense in between. The forms of verbs are called लकरा: 

The following explains mapping of various लकारा: to tenses/moods shown above using भू धातु , एकवचनम् , प्रथमपुरुष: as example for each of the लकार:

• लट् लकार: ( e.g भवति )  represents present tense. 

Both past and future tense have 24hr mark relative to present tense. This 48hr period is referred to as अद्यतन. 

• लृट् लकार: ( e.g भविष्यति ) represents the time period upto 24hrs in the future ( अद्यतन भविष्य ). This लकार: corresponds to future tense in English and other languages. 
• लुङ् लकार: ( e.g अभूत्) represents the time period upto 24hrs in the past ( अद्यतन भूत ).

Beyond 48hr period is referred to as अनद्यतन. Following are the लकरा:  that belong to this class.

• लुट लकार: ( e.g भविता ) represents the time period beyond 24hrs in the future ( अनद्यतन भविष्य ).
• लङ् लकार: (e.g अभवत् ) represents the time period beyond 24hrs in the past ( अनद्यतन भूत ).This लकार: corresponds to past tense in English and other languages. 

There are one more form of लकर: in past tense 

• लिट् लकार: (e.g बभूव ) represents the time period that we have not seen (परोक्ष) - beyond our existence in past - happenings during different युग .

In addition,

• लेट लकार: This लकार: is used only in vedas.

Moving to moods, there are 4 of them, they are as follows.

• लोट् लकार: ( e.g भवतु/भवतात् ) represents imperative mood.
• विधिलिङ् लकार: ( e.g भवेत् ) represents potential/possibility or should/must be done.
• आशिर्लिङ् लकार: ( e.g भूयत ) represents the tense used in blessing someone.
• लृङ् लकार: ( e.g अभविष्यत् ) represents the tense of conditional possibility or possibility dependent on another event.