Are there 12 or 16 tenses in English grammar ? What are they ?

How many tenses are there in English language grammar ? I know about 12, but now I've heared about 16 in total. What are the main tenses in English ?

There are 12 basic tenses in English language grammar, but in total there are 16 tenses. Present tense, past tense, future tense and past future tense are splitted into simple tense, continuous tense, perfect tense and perfect continuous tense:

Present tense
Present simple tense — I do
Present continuous tense — I am doing
Present perfect tense — I have done
Present perfect continuous tense — I have been doing

Past tense
Past simple tense — I did
Past continuous tense — I was doing
Past perfect tense — I had done
Past perfect continuous tense — I had been doing

Future tense
Future simple tense — I will do
Future continuous tense — I will be doing
Future perfect tense — I will have done
Future perfect continuous tense — I will have been doing

Past future tense
Past future simple tense — I would do
Past future continuous tense — I would be doing
Past future perfect tense — I would have done
Past future perfect continuous tense — I would have been doing

Past future tense is also known as Conditional tense, so examples look like:

Conditional simple tense — I would do
Conditional continuous tense — I would be doing
Conditional perfect tense — I would have done
Conditional perfect continuous tense — I would have been doing