Weed seeds are everywhere. Dandelion and Thistle seeds blow in with the wind, Grasses spread their roots into your garden. The hardest way to deal with your weeds is to pull them one by one by hand as they pop-up.
Stale seed bedding is a technique that helps to eliminate the seed stockpile in you soil. The basic idea is to permit the weeds in you soil to grow then kill them. The first step is cultivating your soil, and preparing your soil as though you would plant crops in it. Then you water and wait.
The fast weed seeds begin to germinate very quickly. In a very weedy soil the cultivated patch will become a green blanket. After adequate germination has occurred you kill all the weeds at once. To kill the weeds you can rototill them into the soil; which will return their nutrients back to the soil.
If you want to plant a weed-free crop into your stale seedbed a flame weeder is useful for this application. The flame weeder kills all the weeds without disturbing the soil, which would cause more seeds to germinate.
Stale seed bedding is a useful technique for crops that are directly sown like: leaf lettuce, spinach, arugula, beets, carrots and radishes. These crops would otherwise have to be hand weeded after germination, which, as you many know, is painstaking.
And now you know!