sRules is a simple Expert System software. It allows to assist the user in a chosen domain, like choosing which car to buy, where to go for a dinner or even helping in mortgage banking. To do that it needs a Knowledge Base, which describes how to process facts provided by the user. Knowledge base consists of a list of goals (e.g. choosing a car model, and choosing a car type), questions about facts (e.g. “How much money would you like to spend?”) and rules. At the beginning of the inference process the program asks which goal should be the target. Next, it asks questions about facts needed by rules, which may be used to infer the target. Inference engine uses backward chaining method to perform expertise. To get explanation about the inference process, user may use Explanation Service. It provides answers to the following three questions: WHY the system asks for the fact, WHAT system knows so far, HOW it inferred the fact. After building the appropriate knowledge base sRules can be used to assist the user in decisions in this domain. It can be also applied in education to familiarize pupils with the AI methods. The program key features: * Creating, viewing and editing knowledge bases * Running a selected knowledge base * Discovering the first or all the answers for the goal * Explanation services: Why, What, How questions: * Why - why the system asks the question * What - what facts have been gathered or infered so far * How - how every fact has been derived sRules for iOS is available on the App Store.