**3.3 Security overview**

The basis idea of pooling has been always employed by humans. Its most evident and valuable advantage is cost and resource optimization, but it hides facets that may shadows its benefits. Whenever we share something we are worried since our goods may not be handle properly and may be manipulated by strangers. Moreover when we use someone else stuff we worry about safety since objects may be dangerous, broken or compromised.

The above concept perfectly fits grid system since grid can be seen as a mechanism to pool resources to optimize system utilization. Therefore we can state that security and trust, together with resource monitoring, authentication and authorization of users, and data protection, are essential to Grid Computing. In the following we give an overview of security in Grid Computing by using the classification proposed by Chakrabarti (2007). As shown in Figure 4, he categorized grid security issues into three main categories: architecture, infrastructure, and management related issues.
