There is a difference between a clean beer glass and a beer clean glass. A clean beer glass means that it is sanitized and nobody is getting ill. Check.

Beer Clean is an industry term to explain that a beer glass is free from oil and grease inside the glass. And...it has a massive impact on how your beer is going to taste and look.

Here's what you need to know:

• Dirty glasses have an invisible film of oil and grease on the inside.

• This is caused by putting fingers, pop, dairy based drinks, or napkins inside the glass. Or by running your beer glasses through the dishwasher, not the glass washer.

• This gives the beer poor head retention and makes it go flat quickly.

• A Beer Clean glass has lacing - Rings of foam left on the inside of a freshly consumed pint glass, like this image to the right.

Most pint glasses in the industry are not beer clean.

Here is Steve Riley, Certified Cicerone® and Founder of BetterBeer.com in a short video explaining the difference: