Chances are, at some point in your life and travels you will need to create a makeshift shelter for its survival benefits. This could be due to a hike that ran late or resulted in getting lost or perhaps because the SHTF has run you from your home. Regardless of the reason for it, knowing how to assemble a temporary shelter is advantageous for keeping you dry and buffered from the elements.
One good thing about Mother Nature is that she always provides. What she provides, however, can vary and it is up to you to know how to use it. When it comes to seeking out a temporary shelter, the first thing you should do is look for something already usable. This could be a rocky overhang or a cave, something you can get under or into to prevent exposure to the elements. Finding such a shelter is ideal, but there are still things to consider before boldly going inside. If that shelter looks good to you, chances are it may have also looked good to someone or something else. Since bears, wolves, and venonmous snakes are not known to hang a 'no vacancy' sign, it is best to look for clues around the shelter that can tell you if something is definitely inside. Good indicators of residence are foot/paw prints, or slide marks in the case of a snake, as well as fecal matter. You may also be able to smell the musky odor of a furry resident. If you do not take note of anything that indicates to you that something is living inside, proceed slowly and continue to exercise caution. Tenants may not be home at the time but very well could return and you will need to prepare for anything, up to and including your own escape.
Since there are risks associated with possibly denning up with a predator by accident, you may want to skip cave exploration and settle for building your own A-frame shelter. You can do this with sticks or tree limbs and dry debris that is usually scattered plentifully upon the forest ground. To start, you will need a sturdy limb to act as the backbone of your project. It is best if you can find something against which to angle it, such as a downed tree or even the trunk of another tree. With the rope (paracord!) you should always have handy, secure this limb in place. Then collect other sticks and limbs that are long/tall enough to reach from the backbone limb to the ground. On both sides of your backbone limb, alternate sticks, positioning them so they lean atop the backbone and reach down the ground. Imagine that you are creating a triangular tent out of sticks instead of canvas, as that is essentially what you will be doing. Once you have sticks in place to create a good barrier between the inside of your shelter and the outside world, cover it with whatever possible, such as fallen leaves or pine straw (be sure to keep an eye out for poisonous plants!). When you have completed this process, all there is left to do is fashion a door in much the same manner and crawl inside to ride out the night.
Having to unexpectedly shelter in the woods is likely not a terribly exciting prospect, but these things happen. With the survival items you should always be carrying (rope, knife, etc), you can fashion a shelter that will get you through the night. Always exercise caution both when seeking and building shelter as other animals may be present in established shelters or may decide they like the looks of your new one. Make your shelter as secure as possible but always pay attention and stay aware; you do not want things that go bump in the night to come bumping into you.