Ch'ing Ming is a practice whereas family members--usually the whole household from grandparents to the littlest ones--go out at night and burn fake paper moneys, paper houses, paper accessories which they think by doing this kind of practice, can go to the underworld to the dead relatives. They do this on a specific date they calculated on the "farmer's calender", usually around April. With the belief that the date they chose is the date in which the underworld gate opens, by burning their relatives things such as paper money, their deceased relatives can receive, on this day. They believe that the underworld gate closes again within certain hours, so they have to burn the paper money within those hours.
Although that some people don't believe in Ch'ing Ming anymore as they think it's superstitious which doesn't connect to the modern world anymore, it still exists and is still practiced in many areas around China. That's because they believe by bringing their dead relatives money, in exchange of a favor, those dead people can bring them good spirits, good fortune, good luck. That those dead spirits and make their roads in the real world wider, can bring them more opportunities in order to survive and such. With the little ones in the household, they believe that the dead from the underworld can bring health to children since children have a weaker immune system.
However another reason to practice Ch'ing Ming is that they believe since it's the only day the underworld connects the real world, and through burning scented wood sticks, which is kinda like a communication method, that the smoke acts as the medium --- they can talk monologues to tell those deceased relatives how they are doing today.
For example, those monologue might be: "Hi, big brother John, I miss you dearly and feel sorry about it that you have left us, for all of our family members miss you dearly since you've passed away. How are you doing over their? We are good. Sister Mary's kid Mat got into one of the top colleges in the world. Brother Sam's company is earning big money... Please continue to bring us good luck and fortune big brother John and we hope you don't feel lonely down there!"
A lot of Chinese I know don't believe that those paper money can really reach to the underworld now, especially Chinese in the modernized city. Ch'ing Ming is still practiced, however, as it's a form to remember the relatives.
As a conclusion, Ch'ing Ming still continues as a practice today however it's meaning may has changed to just a memorial to the deceased relatives.