Why is it that the holidays suddenly put people in a charitable mood?

Around the holidays, charities always become a big focus. You see canned food drives, Salvation Army bell ringers, and toy drives everywhere. School clubs and organizations decide to adopt families/children, and a donations to charities have become a popular gift.

While I applaud all of the charitable involvement and I certainly don’t mean to undermine it, I really don’t understand why people only seem to become so engaged in charitable activities during the month of December. It’s not as if the people receiving the help, whether they be a person living in a local homeless shelter or an impoverished village in Africa, only need said help during the holiday season.

Why is it that people (including corporations) who wouldn’t make even the smallest effort to help the needy during the other eleven months of the year suddenly decide that they want to make the world a better place?