Answer by Shreyas Panhalkar:
's answer inspired me to write this. I am elaborating the second and third point mentioned in his answer.
I found it very fascinating the way in which Hindus measured/measure Time. Time in the Hindu scriptures is believed to be circular rather than linear. Time is "Anaadi"(अनादी) and "Anant"(अनंत). Anaadi means something which has no beginning and Anant stands for "Endless".
Read the following sentence and you will be amazed.
"At this time we (our solar system) are experiencing the last part of Kali Yuga of the 28th Mahayuga of the 7th Manvantara of the Kalpa"
Now let me explain some terms mentioned above.
Kalpa is a vast, cosmic time period also known as “a day(only day) of Brahma (God)”. Each new creation cycle begins a new kalpa. Name of the current kalpa is ShvetaVaraha. Approximately 4.32 billion solar years constitute one Kalpa.
Each kalpa is divided into 14 Manvantaras. We are in the first phase of 7th Manvantara –Vaivasvata.
Each Manvantara is divided into 71 Mahayugas i.e. one Manvantara lasts 71 Mahayugas.
4 yugas make one Mahayuga. Sat yuga(or Satya), Treta Yuga, Dwapara Yuga and Kali Yuga are these four Yugas.
Sat Yuga is sometimes referred to as "Golden Age" or "Era of Enlightenment" and each Yuga that follows is progressively “darker”. Kali Yuga is believed to be "Age of demon" or "Dark age".
Duration of each Yuga is mentioned in the following image-
These greater delineations are followed by further diminishing designations
of the time such as year, the half-year, the season, month, fortnight, and tithi.
Samvatsara is a period of one year. In all, there are total 60 names given to each year. Each name repeats after 60 years which is the period taken by Jupiter to orbit the sun 5 times!
These are the 60 year names.
Ayana is equal to the period of half year.Each year is divided into two halves, known as Ayana. Uttarayana begins on the day of the winter solstice,
normally December 21, when the sun begins its apparent northward journey.
Dakshinayana begins on the first day of the summer solstice, normally June 21,marking the sun’s southward movement.
Rutu is nothing but a season. There are total 6 seasons in a year,and each season lasts 2 months (Masa).
1. Vasanta (spring)
2. Grishma (summer)
3. Varsha (Monsoon)
4. Sharad (Autumn)
5. Hemanta (Winter)
6. Shishir (prevernal)
Maasa means month. There are toatal 12 months in Hindu calendar(Lunar).
Shaka and Chaitradi Vikram(kind of calendar) start with Chaitra while Kartikadi Vikram starts in Kartika.
Paksha refers to Fortnight.One month is the duration of one orbit of the moon around the earth. In Hindu measuring of time, this period is divided in two parts, the light fortnight,called shukla paksha, and the dark fortnight –krishna paksha .Shukla Paksha is the period when the moon is waxing, beginning on the new moon (Amavasya) and extending to the full moon (Purnima). Krishna paksha, the period when the moon is waning, begins after the full moon and extends to the new moon.
A tithi is an exact lunar day, which is approximately one-thirtieth of the time it takes the moon to orbit the earth. There are total 15 Tithis in one Paksha or fortnight. 15 Tithis are :
Prathama, Dvitiya, Tritiya, Chaturthi, Panchami, Shasthi, Saptami, Ashtami, Navami, Dasami, Ekadasi,Dvadasi, Trayodasi, Chaturdasi and Amavasya/Purnima.
Purnima, full-moon day, is the fifteenth tithi of the bright fortnight, and Amavasya, new-moon day, is the fifteenth tithi of the dark fortnight.
You can read further divisions of time in this answer –.
If you are more interested in knowing hindu calendar, see this
Sidenote: It is said that 5,100 years of Kali Yuga had already elapsed before 1999. It is also said that one of the indications of the arrival of Kali Yuga was the curse given to the king.(Read this if you are interested ).
The creation and destruction of the universe is a cyclic process, which repeats itself forever. The universe endures for about one day of Brahma and then is destroyed. New universe is created again. It is believed that 50 years of Brahma have elapsed, and lifespan of Brahma is about 100 years (311 Trillion, 40 Billion Human Years.)