October is the 10th month on both the old Julian and newer Gregorian calendar. It is the first full month of Autumn where harvests are being done and in the old days, people began to make ready for the coming of winter. The southern hemisphere though October is the first full month of spring. Harvest festivals are common at this time of year along with popular ones such as the German Oktoberfest.
Also for sports fans in the US you see the popular sports of basketball, American football, and baseball converge on the calendar. Football is kicking into gear, basketball is starting up and baseball enters its championship phase culminating with the World Series.
Of course the big day is Halloween on October 31st. As it set by date, the exact day it will fall on will vary each year. When it falls on a weekday, it means kids have to be home early as they go to school the next day. Friday and Saturday are optimum as you can have longer Halloween events and stay up late watching scary movies. Halloween is not an official holiday but comes close to it. October has as its flower the Calendula and the birthstone is the opal.