It was the Ching Ming festival the day we left, so we didn't see it in action. Ching Ming was, apparently, instituted by an emperor thousands of years ago because people were spending too much time on ancestor veneration (presumably not working hard enough to generate tax revenues, not being sufficiently on hand to die on the battlefield for the Emperor's glory etc.) so he said that it would only be permitted on one festival day each year. Chinese people will sometimes travel a long way to visit the family graves, tidy them up, make offerings etc. If they can't visit, they may carry out ritual activities at home or maybe at the temple to link them with the ancestors.
I was interested to note that many graves looked to be in a pretty wild state. The graveyards were not in a separate tidy enclosure cf UK, but were grouped together out in the countryside, often on a hillside (de rigeur, apparently. Maybe fung shui dictates.) In a subtropical region, this meant that natural vegetation encroached somewhat. This grave was an exception. It was slap bang in the middle of a village, as you can see, and pretty well-groomed. So these ancestors were right there to keep an eye on things.
The Ghost (or Hungry Ghost) festival is sometimes lumped in with Ching Ming but it seems there is a difference. The Ghost Festival is about easing the lot of any spirits that are moving between this world and the next, at the time of year when the gates between the two open. (cf All Souls, Dia de los Muertos, Jour des Morts, which may ostensibly be about easing the passage of souls in purgatory but also seems to contain, historically, a lot of placating of the returning spirits? I'm no expert here, I merely seek to offer morsels for further reflection.)
So Ghost Festival is in general about the spirits of the dead, and is placatory. Ching Ming is about venerating one's ancestors, as the ultimate shore of filial piety, that cornerstone of Confucianism. People often refer to ancestor worship as being very Chinese; it might be more accurate to say that ancestor veneration is the point. Gran isn't worshipped as a divine being, she is venerated for having been a matriarch etc. Family records and photos are often stored on display in the neighbourhood temple. (Sorry, no photos allowed.)
There has been some interesting stuff in recent months over on the Good Funeral Guide and its commentariat about shrines and the family. I don't know about visiting graves and lighting joss - most or many UK graves don't seem to me to get a lot of visiting, and I remember reading somewhere that the average for a grave to get visited and tended is ten years. But I increasingly like the idea of family shrines, and some kind of regular family day, to tie in the living with their ancestors. Maybe more and more of us value our ancestry and our family (vide TV progs on the subject) and maybe it helps us deal with the pace of social and technological change - sheet anchor stuff.
Ancestor veneration, filial piety and Confucianism in general (even Mao couldn't stamp it out) are often blamed for the perceived stagnation of Chinese culture and techology during the last Imperial dynasty. I wouldn't know, but there's nothing stagnant now about the way China is amassing economic and political power, at huge environmental cost...and the ancestor business still seems to be going strong. We'll see if capitalism and the consumer society destroys what Maoist totalitarianism, murder and starvation couldn't.
How ancestor veneration goes if you have a ghastly ancestor, I don't know. Presumably the ancestors of mass murderers get little veneration. I understandhat the party line in China is that Mao was right 70% of the time and wrong 30% I'm not quite sure that ratio's quite right....
The whole ancestor veneration/ghost festival stuff may look like a lot of superstitious irrelevance, colouful but nonsensical. I find it more useful to mull over its significance, for the living here and over there.
Meanwhile, this little village in southern China gets up each morning and finds a presumably venerated ancestor (and a memento mori) right by its front door.