Ramadan is the ninth month of the Islamic lunar calendar, and lasts either 29 or 30 days, depending on when the new crescent moon is (or should be) visible.
The Arabic term Ramadan connotes intense heat. It seems that in pre-Islamic Arabia, Ramadan was the name of a scorching hot summer month. In the Islamic calendar, however, the timing of Ramadan varies from year to year. This year Ramadan will begin around May 27; next year it will begin around May 16. (An Islamic year is roughly 11 days shorter than a Gregorian year.)
The significance of Ramadan

Ramadan is a period of fasting and spiritual growth...Read more:https://qz.com/992617/ramadan-begins-on-may-27-for-muslims-around-the-world-this-means-fasting/