* ''First Age of the Sun'' (590 years): Begins with the creation of the Sun and Moon and the awakening of men. It ended with the ''War of Wrath'', the final imprisonment of [[Morgoth]] and the destruction of [[Beleriand]].
* '''Second Age of the Sun''' (S.A., 3441 years): Begins after the end of the ''[[War of Wrath]]''. Contains the destruction of [[Númenor]] (T.A. 3319). Ends with the defeat of Sauron in the ''[[War of the Last Alliance]]''.
* '''Third Age of the Sun''' ''' : (T.A., 3021 years): Began after Sauron's defeat by the Last Alliance. Contains the events of ''[[The Hobbit]]'' (T.A. 2941) and the [[The Lord of the Rings|War of the Ring]] (T.A. 3018-3019). Ends with the destruction of the [[One Ring (Middle-earth)|One Ring]] and the defeat of [[Sauron]].* '''Fourth Age of the Sun''' ''': followed the defeat of Sauron and the One Ring, but started officially when the Bearers of the [[Rings of Power|Three Rings]] left for the West. The Elves dwindle and leave, while the realms of Men prosper, becoming the dominant people of Middle-earth.<ref>J. R. R. Tolkien, ''The Lord of the Rings'', Appendix B</ref>
There exist several calendars, as the different peoples created their own or adapted them from older systems. Another important calendar for the books is that of the [[Hobbit]]s: the '''''Shire Calendar''''' and the '''''Shire Reckoning'''''. The Shire Reckoning (S.R.) starts with the colonisation of the [[Shire (Middle-earth)|Shire]] in T.A. 1601 as year one. The Shire Calendar and Shire Reckoning was used in the Shire and in [[Breeland]].<ref>J. R. R. Tolkien, ''The Lord of the Rings'', Appendix D</ref>