Does any one know what is Industrial spying?

Industrial espionage is nothing but keeping tabs on the strengths and weaknesses of competitors and these days it is too common a practice for big houses to frame strategies based on the inputs of industrial spies.

Industrial spying is an attempt to access information about a company. It can be practiced in various ways:
1) A laid off or a fired employee may provide information for the sake of some price.
2) The company's employees may leak out the private information in oreder to double their income.
3) A company's computer may be hacked to gain private information.
4) The company's information is stolen and sold to other company.
5) By using spyware programmes which give more complete information about a company's computer user.

From my practical experience,I can say that companies do plant insiders and rely on the information provided by them!

I have my practical experiences in this matter where we plant our engineers, researchers and marketing professionals in competitor's organizations to get a perfect feedback on every activities. These things are common in every big industry and in every country.