If you're installing hardwood floors in your home, it's very important you let your floor acclimate, or adjust, to the temperature and humidity levels in your home.
Because wood tends to contract and expand, depending on changes in temperature and moisture levels in the air. It's okay that the wood flooring does this. But you have to make sure it's installed the right way or you'll end up with big problems.
If you install a wood floor straight out of the box that has been sitting in a warehouse for weeks or months, you may end up wasting a lot of time and money. For example, if the wood was stored in a cold temperature, the wood would be very contracted. Or if the wood was stored in a warm, humid climate it would have absorbed a lot of moisture and expanded (sometimes by several inches.)
So, if you were to install "contracted" wood in a room and put the wood all the way to the edges in a room, where will the wood go when it adjusts to the warmer indoor air temps? The contraction of the wood will ease and push out, causing the boards to warp, push up, crack and more.
To prevent problems, make sure the wood has had time to adjust to your indoor climate. This way you know you're getting a flooring board that is acclimated and the dimensions are accurate at installation. How long should you leave the boards indoors before you install? You should open up the boxes the wood flooring comes in and let them sit for 3 to 5 days.
Also, it's important to make sure you do not install the wood flooring all the way to the walls in a room. Give space on all sides to allow the wood to expand contract in the winter time and expand during the hot summer months. Allow at least a 1/4 inch space to let your wood flooring move and shift, without destroying all your hard work and money invested.