For decades, clothes dryers did not change a great deal. The basic principle of injecting heated air and drawing out moisture as clothes tumbled in a drum was the same in all makes and models, gas or electric powered. There were much fewer choices than on a washer. Just pick the temperature cycle and length of drying time.
That same design remains in basic dryer models but in more expensive dryers, the addition of a steam cycle has added another choice to clothing care.
If you use the same setting for every dryer load, you're probably not getting the best results from your dryer. Unless all of your laundry loads are exactly same size and type of fabric, you can be wasting money on energy costs, lessening the lifespan of your dryer, and damaging your clothes.
Air Dry or Air Fluff Cycle
On this cycle, there is no added heat. The dryer simply pulls in fresh room temperature air and the drum turns and tosses your clothes to help them "fluff-up". The cycle does help remove dust, lint, and pet hair from fabrics by drawing them into the dryer filter screen. Air dry is particularly useful for fluffing pillows or down-filled items like coats and comforters. You'll get best results by adding a few wool dryer balls to provide a beating action.
This cycle is also great for freshening dry clean only clothes or those that have been stored and smell musty. Add a dryer sheet or a damp cloth scented with essential oil to add a bit of freshness and help tumble out wrinkles.
Remember, the air dry or air fluff cycle will not completely dry wet clothes.
Delicate or Gentle Cycle
As this cycle clearly states, this is a gentle drying cycle for delicate fabrics. While women's "delicates" like bras and panties should never be placed in the dryer, there are other thin or lacy fabrics that fit the description.
Any garment that is loosely woven; made of rayon or silk; or has added embellishment from light beading or sequins, embroidery, or iron-on decals (sports jerseys) should be dried on the gentle cycle. It is especially important to use this cycle for high-performance fabrics. These garments cannot withstand high heat. They will fray, stick together, and may fade on high heat.
Permanent Press or Wrinkle Resistant Cycle
The permanent press cycle should be used for almost everything you wear like shirts, blouses, dresses, slacks, jackets, outerwear, even non-cotton socks. While some manufacturers recommend that it be used for any synthetic fabric (polyester); I recommend it for any lightweight cotton, ramie, linen or natural fiber washable garment as well. The permanent press cycle uses a medium level of heat to prevent wrinkling and the damage that high heat can cause. Many of the permanent press cycles on today's dryers have a cool down period of around 10 minutes that uses only room-temperature air to help relax wrinkles in fabrics. A cooler fabric will not wrinkle as badly when folded as fabric at a higher temperature.
Permanent press does not mean that your clothes will come out of the dryer completely wrinkle free. You can also reduce the need to iron by promptly removing the clothes and hanging or folding them.
Regular Cycle, Automatic, or Timed Dry
This is the cycle for towels, sheets, sweats, and jeans.
Whether you choose automatic dry that uses a moisture sensor to determine if your clothes are dry or select the amount of time you feel the clothes need, the regular cycle is going to use the highest heat setting available on your dryer. While it doesn't really shrink your clothes (the hot water in the washer does that), it can melt decorations, and set stains and wrinkles.
The moisture sensor will only work efficiently if you keep it clean. Regular use of dryer sheets leaves a coating of residue that prevents the sensor from working allowing clothes to overdry and waste your money. Dip a cotton swab in rubbing alcohol and give it a good cleaning every month.
Remember, high heat is harsh on fabrics; choose it only for the strongest fabrics.
Some dryer models have a feature that creates steam within the drum independent of the traditional drying cycle. The steam cycle is good for refreshing clothes that don't need to be washed but need a little odor and wrinkle removal. The moist steam does not aid in the drying process.
The steam cycle can also be added at the end of a drying cycle to prevent wrinkles if you forgot to remove the clothes promptly from the dryer.