Summarize the following:
Fumes from stain or varnish can be harmful to breathe. If the room you’re working in has external windows, open these as wide as possible. If you’d like to take a further safety precaution, rent a vapor-rated respirator  and wear it while you’re staining the pine floor.  You can rent a vapor-rated respirator at a local hardware or home supply store. Since you’ll be working with the windows open, it’s advisable to finish the pine flooring on a warm, rain-free day. If you are not impressed with the natural color of the pine flooring and would like to darken it, you can purchase a stain to seal and darken the pine. Visit your local paint store and ask to peruse their stain selection. Speak with the sales staff to determine which brand and variety of stain is best for your flooring, considering its location in your house and the amount of use it will receive. The major difference between stain and varnish is that varnish will dry clear while stain will darken the color of your flooring. So, if you prefer the natural color of the pine flooring and just want to seal it to protect against moisture and scratches, opt for a varnish. Unlike oil, varnish adheres to the top of the wood without soaking deep into the grain. Consequently, you can remove varnish if you decide to. Oil cannot be removed from wood. Oils are a traditional softwood finish that will penetrate deep into the pine flooring. Oil finishes—unlike many varnishes—won’t peel or flake, and often look better with age. Types of oil commonly used to finish pine floors include:  Tung oil, which has a relatively low level of sheen. This leaves the pine with a more “natural” appearance. Linseed oil, which is tarry and so brings out the grain of the pine. Lemon or walnut oil, which are considered specialty oils and may be more expensive. Before you stain the entire floor, test the stain in an inconspicuous are to make sure that you like the color. Apply the stain using a 3 in (7.6 cm) paintbrush. Let the stain dry for 24 hours.  If you like the appearance of the stained sample patch, you can proceed with staining the entire floor. If you don’t like the appearance of the stained wood, select a different colored stain. Or, if you realize that you prefer the natural color of unstained pine, opt for a clear varnish instead.

Summary:
Ventilate your working area. Choose a color of stain if you’d like to darken the pine floor. Select a clear varnish if you prefer not to alter the pine’s coloring. Apply a colorless oil to preserve the pine’s natural color. Test the stain out on a small corner of flooring.