Plain English Campaign Limited (PEC) is a commercial editing and training firm based in the United Kingdom. It was started in 1979 by Chrissie Maher. The company advocates for the use of simple ("plain") English. It tries to persuade organisations in the UK and abroad to communicate with the public simply. In 1990, Plain English Campaign created the Crystal Mark, its "seal of approval." This is a symbol printed on documents which the Plain English campaign thinks are very easy to understand. According to the Plain English Campaign, the symbol appears on over 20,000 documents worldwide.