Childbirth is a completely natural process, and so is the pain that typically accompanies labor. Pain relief options during labor range from natural methods, which can ease but not eliminate the pain, to epidural or spinal pain medicine that eliminates a majority of the pain. Note the word "majority;" there's no silver bullet that will allow you to have a pain-free delivery.
Each method of pain relief has pros and cons, so you'll have to decide the route you want to take in childbirth. For example, if you use an epidural (spinal anesthesia), you'll feel a lot less pain, but you'll have less control while pushing the baby out. This leads to an increased chance of tearing and the need for stitches. If you opt for an all-natural, no-pain-relief delivery, you'll have much more control when pushing the baby out, but a lot more pain.
It is good to think about pain management before you need it, instead of waiting until you're in the delivery room to make a decision.
Natural Methods
The breathing exercises that you've been practicing during your pregnancy (perhaps even in Lamaze or birthing classes) will help during the early stages of labor. Switching positions often can also help to ease the strain and discomfort (and hopefully get the baby moving around and ready to come out). Your husband can apply ice packs and heat to your lower back as well, or even give you a low back massage. Many delivery rooms now have the option to put on some light music, and some also provide a shower and a tub. All of these can work to alleviate some of the pain or at least take your mind off it; but again, there's still going to be some pain.
Spinal Anesthesia
A spinal is delivered by injection of an anesthetic into the tissue that covers your spinal cord. It's a fast-acting pain relief method for labor, and it requires less medicine than an epidural. However, it has an increased risk of side effects such as headaches or a drop in blood pressure.
Epidural
With an epidural, the anesthesiologist injects the medicine directly into the spinal column. Both an epidural and a spinal are injected into your lower back, and they greatly reduce the pain from contractions. The needle stays in you for the duration of the process, and the anesthesiologist can administer more or less medication over time. The most skilled anesthesiologists will be able to time the reduction perfectly so that the pain medication wears off right as you're ready to start pushing.
An epidural and a spinal are both forms of regional anesthesia, meaning they affect a certain region of your body (in this case, from your lower back and waist down through your toes). They can also be used in the case of cesarean delivery.
Walking Epidural
A "walking epidural" uses the same principle, but it involves a combination of spinal and epidural medicines. It uses less medication than a regular epidural. It provides less pain relief, so you'll still feel the contractions (whereas the other methods leave you feeling virtually paralyzed below the waist). Many women are able to walk around during this form of pain relief, hence the name. Walking helps stimulate the birthing process and will often speed up the delivery time. However, some medical facilities won't allow women to walk around during a walking epidural due to legal concerns.
Systemic Medications
Sometimes pain medication, such as Morphine and Stadol, can be administered through an IV during the birthing process. Opiates and other narcotic medications like these can take the "edge" off the pain, but allow you to push during the birthing process. While these medications can reduce the pain, they can also make both you and the baby drowsy. This can have the negative effect of drastically increasing your delivery time, so these pain medications are typically only used during the very early stages of labor.
General Anesthetic
General anesthesia is safe to use during childbirth, but it's rare. Doctors tend to only use this method in assisted birthing cases that involve an extreme or life-threatening emergency. That's because general anesthesia will put you completely to sleep, preventing you from pushing the baby out and will make you miss the birth of your baby.
Alternative Methods
Some birthing centers offer alternative methods of pain relief during labor, aside from those listed above. These vary from clinic to clinic but can include things like hypnosis, acupuncture, and water immersion births. These methods won't eliminate pain, but like many natural pain relief options, they can alleviate some of the discomfort.
The bottom line is that you'll have to make the decision on how much or how little pain you'd like to experience during labor and childbirth. Here's a good rule of thumb that covers most of the options: medication or regional anesthetics will mean less pain, but possibly a longer delivery time. No medications or anesthetic means more pain, but potentially a much shorter delivery time (and you get to meet your baby sooner).