A Class Action is a lawsuit in which many claimants can join together to sue a company or person in one lawsuit, rather than multiple lawsuits. In many cases, these claimants wouldn't start their own lawsuits because the amount of money they could win would be too small to justify the legal expense. While it's not usually practical for any one purchaser of a defective product to sue a large manufacturer, the total of all the damages suffered by many purchasers may be very large.

• No cost to the plaintiffs: the lawyers usually get paid a percentage if they win, and also pay for the costs, such as expert reports, investigations, and so on
  
  
• Individuals can recover losses from a wrongdoer, without having to sue individually

• Defective products:
  Silicone breast implants, faulty product designs, blood transfusion products infected with HIV & hepatitis C etc;
  
  
• Securities:
  Actions against public companies, stock brokerage firms, or accountants, for fraudulent or negligent statements causing loss to stockholders;
  
  
• Nuisance:
  Unreasonable noise or odours;
  
  
• Environmental:
  Noxious or toxic emissions
  
  
• Negligence:
  Plane crashes or accidents causing damage to many victims;