a. Information System
An Information System consists of interrelated components working together to collect, process, store, and disseminate information to support decision-making, coordination, control, analysis, and visualization in an organization.

b. Functions of Executive Support System (ESS) include:

1. Helping senior management make reliable judgments, evaluations, and gain insights into processes or procedures for arriving at solutions.
2. Incorporating data about external events such as new tax laws or competitors to position the organization better.
3. Providing a minute-by-minute view of the firm’s financial performance, including working capital, accounts receivable, accounts payable, cash flow, and inventory positions at any point in time.
4. Delivering real-time information for day-to-day running of the organization.

c. i. Transaction Processing System (TPS)
A TPS is an information system that performs the recording, processing, and executing of daily routine transactions generated through business activities. It is used for tasks such as handling sales orders, purchase orders, payroll, stock records, and invoicing. The main purpose of a TPS is to handle day-to-day business operations, representing the lowest level of organizational information systems.

ii. Decision Support System (DSS)
A DSS is an information system at the management level of an organization that combines data, analytical tools, and models to support semi-structured and unstructured decision-making. It uses data collected by TPS to evaluate business models and assists managers in making tactical decisions. DSS aims to allow managers to consider a wide range of alternative options using flexible and user-friendly tools.