From http://www.lectlaw.com/def/l032.htm
LIBEL
Published material meeting three conditions: The material is defamatory either on its face or indirectly; The defamatory statement is about someone who is identifiable to one or more persons; and, The material must be distributed to someone other than the offended party; i.e. published; distinguished from slander.
Published could be online, in the print media or broadcast on TV, radio
Big companies hire hackers or kites who are very good at covering their tracks. The compensation offered is sufficient to cover their legal fees if caught.
When you ask them how much they are being paid, you are asked to provide proof of their activities.
There are certain advantages of getting a Cease & Desist letter – you get very good insights into the company who is sending it and also a free template for the letter which you can use at a later date. The letter will be written by a lawyer who has been paid hundreds or thousands of dollars.
It is difficult to find unbiased reviews about some companies online . This is because they monitor the internet very closely and if you post anything negative about them, you will get a cease and desist letter.
They will hire lawyers who are paid hundreds of dollars, but will not pay amounts less than $10 in time to their debtors.  They will then threaten their debtors and make false claims of payment.
Is there real freedom of speech online?  Offline if payment is not made, you can take the party defaulting to court to recover payment.
Online, you lose both your money and are issued gag orders.