From counting them on our knuckles to writing them on the corner of school notebooks, we are well-versed with the concept of the dates and months based on the Gregorian calendar. It is something ingrained in us. We know by heart which month has how many days, all the sun signs, the festivals and holidays that fall during the 4-week plus tenure of each month. But we've never taken the trouble to actually ask why they have been named so.

Well, maybe it's time that we learnt that. Here's how the months of the year got their names:

Since January is the first month of the year, it's seen as a doorway to the new year. Hence, it was named after Janus.
The festival of washing away all sins was celebrated during this month. The month therefore got its name after the festival's name - Februalia.
In Roman times, it was the first month of the year. It was the month when the harvest began. It was also the month when wars and battles were deemed unfit.
Since a few months had already been named after gods & divinities, the Venerelia celebrated in honour of Venus was held on the first of this month. Originally it was named Aprilis (original etymology from aperire), derived from her Greek equivalent Aphrodite.
Bona Dea's festival was held in May. The month got its name from her Greek equivalent Maia. Roman poet Ovid, however, stated that May was named for Maiores which means elder in Latin and the following month of June was named for iuniores (junior or youngsters).
Apart from the etymology Ovid suggested, it is said that June got its name after the wife of the supreme deity Jupiter named Juno, who was the goddess of marriage.
Since it was the month when Caesar was born, it was named after him. Before that, it was called Quintilis (Latin for 5).
Before Augutus, it was named Sextilis (Latin for 6).

The months from September to December were named in the order of appearance on the calendar. Since there were only 10 months on the calendar initially, they were numbered from 7 to 10.

January and February were added later, thus giving us a total of 12 months. 

Design credits: Utkarsh Tyagi