Look closely at any plastic packaging nowadays and you'll find a small chasing arrows symbol with a number between one and seven inside of it. That symbol is synonymous with recycling, but it's also misleading. 

According to Natalie Lennick, environmental activist and founder of Green Ablutions, the chasing arrows symbol, also known as the resin identification code, indicates what type of plastic it is. "It's a generic symbol that does not indicate recyclability," Lennick says. 

Resin identification symbols identify the seven most common types of plastic, and are important to understand because municipal facilities, like the ones that handle your curbside pickup, can't process every single type of plastic. 

In short, the symbols tell you what you can reuse and recycle safely. But it's your responsibility to sort plastics according to the rules of your local recycling program. Here's a full breakdown of each plastic recycling symbol. 

Important: Pay attention to your local guidelines on recycling. "Wish-cycling non-recyclable materials into the waste stream may contaminate an entire batch of recycling down the line causing further harm," Lennick says. "When in doubt, throw it out."

PET, also known as PETE or polyethylene terephthalate, is among the most common types of plastic. It's a lightweight, clear resin, and is more energy efficient to produce and transport than other types of plastic.

Common products: Soft drink, juice, and water bottles, salad dressing containers, peanut butter and cooking oil jars, and mouthwash.

Can it be reused? Short answer, yes. PET is approved by the FDA for single and repeated use. Over time, reusing the same PET water bottle, for example, will cause it to leach chemicals into the contents, but it happens at such low levels that it's not a health risk. 

Can it be recycled? Yes – PET is fully recyclable, and is in fact the most recycled plastic worldwide. "PET can be woven to form polyester fabric or carpeting," Lennick says.

HDPE stands for high-density polyethylene, an opaque plastic made with petroleum. It's another common type of plastic for consumer goods because it's rigid, durable, and can withstand stress – therefore, it has a wide variety of uses.

Common products: Milk jugs, bottle caps, food storage containers, laundry detergent, fuel cans, toys, outdoor furniture, plastic mailing envelopes, and milk crates. 

Can it be reused? As long as you wash them out thoroughly, HDPE containers are safe to reuse. 

Can it be recycled? Yes, HDPE is generally accepted at most recycling centers.

Quick tip: Whether you're using it for food storage or not, it's recommended to wash out every type of plastic you plan to reuse with warm, soapy water to prevent the buildup of bacteria. For health reasons, Lennick says you should never reuse a container for food if it previously held a non-edible or hazardous substance.

PVC, also known as polyvinyl chloride or vinyl, is the third most widely-used type of plastic in the world. It's very strong and comes in both a rigid and flexible form, so it's a versatile, economical plastic. 

Common products: Siding, window frames, plumbing, flooring, IV bags, bank and membership cards, imitation leather, and inflatable items. 

Can it be reused? PVC is quite durable, so it tends to last a while, but is not generally safe to reuse. However, some organizations like Habitat for Humanity accept gently used PVC donations to reuse in their builds.

Can it be recycled? PVC is highly recyclable, but it's not meant to be mixed in with your general recycling. You can, however, store PVC in a separate bin and recycle it at special facilities. Earth911 has a recycling database to help you find such facilities nearby, though you should contact the recycling center directly for more details.

Low-density polyethylene, or LDPE, is HDPE's less-rigid counterpart. It's relatively transparent, and is less dense but more resilient than other types of plastic. 

Common products: Bread wrappers, cling wrap, grocery, trash and dry cleaning bags, thin container lids, squeezable bottles, and the lining of diapers, paper juice cartons, and coffee cups.

Can it be reused? Yes, so long as the bag or container didn't previously hold something harmful or non-edible.

Can it be recycled? Yes, but not usually at municipal facilities. "Since flexible plastics tend to get tangled in the machinery they need to be returned to the grocery store for separate recycling," Lennick says. Search your ZIP code at BagandFilmRecycling.org to find out what stores near you participate in plastic bag recycling.

Polypropylene, or PP, is a highly durable form of plastic. It's tough, has a slippery surface, and is less dense than other common plastics, so it's useful for items that need to bend without breaking.

Common products: Takeout containers, prescription medicine bottles, drinking straws and cups, bottle caps, and syrup, yogurt, and margarine containers.

Can it be reused? Yes, there's currently no evidence that PP leaches any harmful chemicals. 

Can it be recycled? Yes, many curbside programs accept it. PP is an easy material to recycle because it can be melted, cooled, and reheated again without degrading.

PS, or polystyrene, is more commonly known as styrofoam. It's lightweight, rigid, and also one of the biggest sources of outdoor litter – which is a particular problem because it takes 500 years to break down in landfills. 

Common products: Disposable tableware, medical equipment, meat and poultry tray packaging, smoke detectors, packing peanuts, takeout containers, and building insulation.

Can it be reused? While styrofoam can be reused to mail packages or for science and art projects, the options are limited because it's so brittle. It's best to avoid styrofoam as often as possible due to its highly damaging environmental effects.

Can it be recycled? PS is one of the more difficult plastics to recycle, but there are specialist retailers who can process it. Locate one near you on this map. 

Quick tip: If your municipal facility doesn't process certain plastics, look for special events or centers that can process them. Companies like Terracycle, Preserve, and Matthew 25: Ministries also have mail-in recycling programs for many common household items.

O stands for other plastics, or any mixture of plastics or one that doesn't fall into one of the above categories. It's hard to generalize, so you'll see a wide range of products with this label. 

When resin identification codes were first created in 1988, there were far fewer plastics available than there are now, so this label had  more use then – now, it's used as a catch-all category for a wide number of newer plastics. 

Common products: Baby bottles, DVDs, sunglasses, three and five gallon water bottles, car dashboards, headlights and sun roofs, and medical devices.

Can it be reused? Barring unconventional approaches, such as art or science projects, it can be difficult to reuse number 7 plastic. It's worthwhile to try repairing items that are encased in or made from it before throwing them out, and to purchase second-hand whenever possible. It's also worth noting that many number 7 plastics include BPA, a known endocrine disruptor that's linked to many health concerns, and should never be reused.

Can it be recycled? Since this type is so extensive and diverse, you'll want to do your research as to when and how to recycle number 7 plastics. Earth911.com is a great place to start.

Though most types of plastic are recyclable, each facility has different standards for what they can accept. That's why it's important to understand and identify the seven main types of plastic using their resin identification code, which looks like a chasing arrows symbol with the appropriate number inside.

Plastics 1, 2, and 5 are commonly accepted at curbside programs, while other types may need to be processed in special facilities or tossed in the garbage.