Fasting during the month of Ramadan (also spelled Ramadhan, Ramzan, Ramadhaan), is one of the five pillars of Submission (Islam in Arabic). In the month of Ramadan, submitters (muslims / moslems) fast from dawn to sunset (if able). While fasting (seyam / saum / sawm) during Ramadan, the individual refrains from eating and drinking and practices continence. It is a time of worship and contemplation and to fulfill God's commands and grow one's soul. A time to strengthen family and community ties, and be on our best behaviour.
Ramadan is the ninth month of the Muslim calendar. God revealed the Quran to the prophet Muhammad, on the twenty-seventh night of Ramadan (this night is also referred to as the Layl at-ul Qadr, or the Night of Destiny), 13 B.H. (before Hijrah). This corresponds to 610 AD.
[Quran 2:185] Ramadan is the month during which the Quran was revealed, providing guidance for the people, clear teachings, and the statute book. Those of you who witness this month shall fast therein.

[Quran 97:1-5] We revealed it in the Night of Destiny. How awesome is the Night of Destiny! The Night of Destiny is better than a thousand months. The angels and the Spirit descend therein, by their Lord's leave, to carry out every command. Peaceful it is until the advent of the dawn.
Ramadan This Year (2017)
Ramadan begins on May 26, 2017 and ends on June 23, 2017 God willing for for Western USA & Canada (e.g., Los Angeles, San Francisco, Seattle, Vancouver).
Ramadan begins on May 26, 2017 and ends on June 24, 2017 God willing for Central and Eastern USA, Canada, Mexico (e.g., Chicago, New York, Washington DC, Toronto, Mexico City), South America and parts of West Europe (e.g., London).
Ramadan begins on May 27, 2017 and ends on June 24, 2017 God willing for most of Europe (e.g., Paris, Berlin, Rome), Africa (e.g., Cairo, Lagos, Nairobi, Johannesburg), Asia (e.g., Mecca, Istanbul, Dubai, Tehran, Mumbai, Chennai, Dhaka, Kuala Lumpur, Tokyo) and Australia (e.g., Perth, Adelaide, Sydney), New Zealand
To calculate the Ramadan start date - compare the time of the New Moon with the Sunset in your location. If the new moon is born before sunset, you should fast the next day God willing. Similarly to determine the last day of Ramadan fasting - compare the time of the next New Moon with the sunset in your location. If the new moon is born before sunset, the month of Ramadan is complete on that day.
To find out the start day for your location, and generate a fasting begin/end schedule, please visit the Ramadan Calculation Assistant (courtesy MasjidTucson.org).
Phases of the moon data (including the new moon) for 2017 (and beyond) are available at the US Naval Observatory. All times are in UTC (also known as GMT). To convert to your time zone you can use the Time Zone Converter.

How do I Calculate Time for Dawn & Sunset to observe the Fast during Ramadan?
The time to begin fasts in Ramadan is the same as the beginning of the dawn (fajr) prayer. Similarly, the time we can break our Ramadan fast is the same as that of the sunset (maghreb) prayer. If you do not have a prayer time chart with you, you can calculate the times for your location at the following site: MasjidTucson.org's Fasting & Salat time calculator. Please always verify the times any software gives you by a simple check in the local newspaper for sunrise and sunset (since some software have incorrect data for the local time zone or daylight-savings timings). May you have a blessed Ramadan!