The loose piece

A loose piece in chess is simply a piece that has no protection. It is common for players to leave pieces unprotected here and there; as long as they aren’t being attacked, they look safe enough.

But loose pieces make perfect targets for the double threats described a moment ago. Suppose your queen performs a fork, attacking your opponent’s king and one of his rooks at the same time. He moves his king. Now you can use your queen to take his rook—if it is unprotected. But if the rook is guarded you won’t be able to take it because the cost will be too high: your queen will be captured afterwards.

We can turn this point into advice for practical play. You want to be aware of loose pieces on the board at all times. Any piece your opponent has left unguarded is a possible target for a tactical strike; any piece of yours that is left unguarded is a vulnerability. Indeed, you want to not only notice loose enemy pieces but also look for ways to create them. We will see countless examples in the studies to come. ("Loose pieces" also can be defined to include enemy pieces that are underdefended: attacked once and defended once by a fellow piece. As we shall see, pieces in that condition sometimes can make targets just as good as pieces with no protection at all.)

The great chess writer Cecil Purdy stated the point as a rule: "Never leave or place a piece loose without first looking for a possible fork or pin, and never see an enemy piece loose without doing the same." Do you follow this advice already? Many inexperienced players don't. When they put a piece onto a new square, they mostly just check to make sure it won't get taken there. Purdy's advice is different. It is to ask whether your piece hasprotection on its new square; and if it doesn't, to ask carefully whether a fork or pin or other tactic might be launched against it. You may not yet understand quite what it means to look for forks or pins, but you will soon; and then following Purdy's counsel will save you many sorrows.

Pick friends who back you up. Be a loyal friend and keep loyal friends. How does chess teach this lesson? A piece alone in enemy territory is vulnerable. You see over and over again the direct value of having your pieces guarding and protecting each other. One of the most important principles in chess (one of the things to consider when considering a move) is to make sure when you move a piece forward you protect it with one or two of your other pieces.
I just saw a film last night about wild dogs in Africa. They truly lived the principle of mutual protection. Only the dominant female of a pack has pups. In this pack of about 15 dogs, they all helped her feed the pups. She dug a den and stayed with the pups and never left them. The other dogs would go out hunting and bring food back for the mother. And as the pups got old enough to eat meat, the dogs brought them food too. They looked out for each other.
The den hole was dug in an open area and a vulture found them and was hanging around, hoping to catch a tasty little pup. The other dogs kept chasing it off, but it kept coming back, and other vultures from around the savanna saw the commotion and came over to investigate. Pretty soon the dogs were wearing themselves out chasing off the vultures. So they decided to make a new den in a more protected area, under a tree and bushes.
They dug a new den and then the mother carried the pups to their new home one at a time. And as she went from the old den to the new, she was surrounded by several other dogs, escorting her and protecting her and the pup as they made the trip.
It was a beautiful example of the value of looking out for each other. That's how these scrawny little animals are able to survive in such a dangerous environment.
That's true on the chessboard as well. Your pieces must protect each other. And work together — rarely can you deliver checkmate with a single piece working alone. Usually you have to use your pieces in a cooperative group effort.
In life, you may not need protection from lions, but even modern life has its dangers, some of them aren't physical, but emotional. A good friend can make a big difference.
Choose good quality friends. Choose only a few. And nurture those relationships. Keep them close. When you have an opportunity to show your friend what your friendship means to you, do it.