What is Executive Information System?

Legal Definition
An executive information system (EIS), also known as an executive support system (ESS), is a type of management information system that facilitates and supports senior executive information and decision-making needs. It provides easy access to internal and external information relevant to organizational goals. It is commonly considered a specialized form of decision support system (DSS).

EIS emphasizes graphical displays and easy-to-use user interfaces. They offer strong reporting and drill-down capabilities. In general, EIS are enterprise-wide DSS that help top-level executives analyze, compare, and highlight trends in important variables so that they can monitor performance and identify opportunities and problems. EIS and data warehousing technologies are converging in the marketplace.

In recent years, the term EIS has lost popularity in favor of business intelligence (with the sub areas of reporting, analytics, and digital dashboards).
-- Wikipedia
Legal Definition
Infrastructure source of up-to-the-minute operational data, collected and screened from many databases. Financial information, work-in-process, inventory numbers, sales numbers, market trends, industry statistics, and market price of the firm's shares are the types of information taken from an EIS. While it is not a decision support system (DSS), It may point to potential actions targeted for executives, but not managers. It is neither hardware nor software.