It's a multi-billion dollar a year business worldwide.
But while they add the perfect touch to a romantic evening or holiday at home, some of them may actually be bad for your health.
According to the Environmental Protection Agency, along with researchers at the University of Michigan and South Carolina State, certain types of candles have been found to discharge the dangerous chemicals benzene and ketones, both known cancer-causing agents.
While there have been no definitive studies determining the long term effect of candle exposure, Arizona allergist Dr. Stuart Agren says the chemicals emitted by certain candles, especially heavily-scented ones, are similar to the fumes released by automobile exhausts.
The culprit, according to others, is paraffin wax itself, which is distilled from petroleum products.
"It's a lot like pollution in the air," said Agren. "Hydrocarbons that are coming off that are being burned."
Agren says those chemicals may induce symptoms similar to an allergic reaction. He says they may also trigger asthma attacks.
Agren also says heavily-scented candles can add to the irritation. They often contain a variety of scented oils, the origin of which is not always clear.
Experts say candle buyers can minimize their risk by scrutinizing content labels.
A label which simply lists content as "fragrances" or "secret ingredients" may be suspect.
Other problems can stem from the make up of the candle's wick.
Candle wicks manufactured and sold in the United States are required to be lead free, but that's not necessarily the case in other countries.
One way to protect yourself from possible lead exposure by way of a candle is to peel back the wick. If you see any metal or wire you might think twice before lighting it. While most candle makers use zinc, those manufactured outside the U.S. could pose a problem.
The National Candle Association takes issue with those suggesting candles may pose a health risk.
In an online statement the CSA says:
"No candle wax has ever been shown to be toxic or harmful to human health."
But the EPA says the verdict is still out, especially in terms of long-term exposure.
If you do burn candles, safety experts suggest cracking a window or to otherwise keep the air flowing, especially in smaller rooms, like your bathroom.
Others suggest candles derived from beeswax or soy provide safe alternatives to paraffin-based candles, but those claims have yet to be substantiated. Experts say some of those candles still contain paraffin and that addition of scented oils and other scented materials could pose the same problems seen in traditionally-made candles.