When food in supermarkets nears expiration dates what happens to it.  Do they resell it in other stores?

Some mark it down, others give it to charity. A few sell these items to liquidators.

Walmart puts it on sale / clearance. For others it depends, ask for a manager.

some will reduce the price. some can go to charities (those who look after homeless etc) I have seen a lot eg fruit and

veges

that get thrown out

Many mark it down and what doesn't sell gets donated, especially if the store can get good PR.  Many dump it, and worse, destroy it.  When I was a student I had a part time job with a very upmarket supermarket who NEVER mark anything down because that would attract the riff raff.  Not even the staff were allowed to take it home because we were riff raff with the wages they paid.  One of my tasks was to slash packaging with a box cutter and pour blue dye all over the dumpster.  It was my job, but I still feel dirty about doing that.

No, they donate it, or dump it. Expiration dates are not indicative of spoiled food. They are suggestions by the manufacturer on when the food is at it's BEST quality. Some foods can be still edible and good long past those dates--and some cannot. 

In North America, if it isn't sold after reducing the price, once it is past the 'best by' date it is garbaged. This keeps the store from having to deal with liability issues. Totally disgusting practice considering how many people go to bed hungry on our continent.

Most store have a sell by sale. I buy fresh bread regularly from Tesco on sell by, and other things too if you know the right times.

Mark downs. 

some is returned to the manufacturer

some is donated

some gets tossed out

Dates are not "expiration" dates but "best by, use by, sell by, freshest by" or any number of terms. The only food required to be pulled is infant formula/baby food. 

It is up to the consumer to read dates if you are wanting the "freshest, newest" product on the shelf.

The date is used by the manufacturer as a guide for a guarantee of quality to the consumer. If there is a product you use that is "out of date" they can say it might have been a storage problem if the product does not meet your satisfaction. Most likely they will refund your purchase price (within reason I would not push it with a product 2 years old)

Oils are the main problem they become rancid. Baking powder can become less effective, yeast can die

Food in supermarkets doesn't have “expiration” dates.

What happens as food nears its best before or use by date, or when it is starting to deteriorate depends on the food.

Pretty often things like fresh fruit and vegetables are just thrown out. Some foods would be reduced in price, some would be given to “good causes” or even staff. Some would simply be re-packaged with a new date (fresh meat and fish for example might then be sold frozen). Some would be sold off to shops specialising in cut price goods - the same happens when packaging is changed.

No, they usually reduce the price substantially and it is sold. If it doesn't sell it is disposed of. In some cases, these foods are donated to groups that are feeding homeless in shelters as well as "soup kitchens".