Technically, two (present and past) but commonly, we say there are 12: past simplepresent simplefuture simplepast continuouspresent continuousfuture continuouspast perfectpresent perfectfuture...
Three simple tenses. Three perfect tenses. Six progressive forms. So, twelve. In order: /_Past Perfect_/_Past_/_ Present Perfect_/_Present_/_Future Perfect_/_Future +progressive (continuous) in all...
Technincally and theoretically, there are two tenses: Present and Past. Perfect, future, and continuous are thought of as aspectual in function. However, grammar textbooks usually use twelve...