Software agents are autonomous, they can communicate, and they can learn.
Sometimes they can also travel from computer to computer, in that case they are called mobile agents. Mobile agents can be used for electronic commerce applications. They can for example look for the best price, they can go to an on-line auction to buy and sell products of their owners, they can be instructed to retrieve the most interesting electronic news paper every day, etc. Security, besides intelligence, autonomity, mobility, language, etc, is very important for these applications. Different security problems can be identified.