Salt is a crystal and like all crystals it carries an electrical charge. Salt holds energy. It doesn’t increase it or disperse it—it just neutralizes it. This is why salt is used for protection or banishings. It’s also often used to create a magic circle—keeping energy inside the circle and preventing outside disturbances from penetrating the circle.
Place salt in small dishes on the hearth or in important areas of the home to keep out bad energy. The thing is, salt is programmable like any crystal and so if there is already negative energy in the home, salt may hold it there. Clean the place out and start with fresh salt. Charge it with positive energy as you place it. Then change the salt every week. Sea salt or rock salt is nice, but plain old table salt works, too.
To charge salt, or anything, your intention and your concentration are keys. Concentrate on the intent—what you want to create–as you work with salt. Take your time and focus. If it was easy, everybody would be doing it.
Pretty much every culture uses salt to purify, purge, or banish. Sprinkle salt in your bath to draw out negative energy. In the Highlands a bowl of salt is sometimes placed on the chest of a dead person to prevent bad spirits from entering. Sprinkling salt on the doorstep to keep out bad spirits done in more than one culture. If you want to prevent a negative person from coming back, throw salt after them as they leave. Take salt to welcome neighbors into a new home and put salt in the four corners of your own home to protect it from all sides. A Japanese custom is to place a bowl of salt outside the door to purify those who pass through. A handful of salt is thrown into the ring before a Sumo match to keep evil spirits away. In da Vinci’s The Last Supper, Judas has just spilled the salt—a very bad omen. Holy water has salt in it.
I’ve even seen advice to put a bowl of salt on a finicky computer, presumably to disrupt the purple techno-gremlins from the planet Dammit. This one I will be trying this week!