Background: It is a global challenge to assist the ever-growing elderly populations__ampersandsignrsquo; needs. There are needs related to healthcare, ageing in place, security, social and well-being of the elderly. Activity recognition enables continuous monitoring and prevents a hazardous situation such as falls. Objective: This paper discusses the type of sensors and processes involved to support the elderly to stay in their home independently and continue their routine activities. Although this technology has been around for a long time, it has not been implemented in elderly homes. Conclusion: This multi-level processing system has many benefits if the data is processed to fit the needs of the resident ambient environment. However, the majority of the research detects single user environment almost perfectly. This paper focuses its attention on research on composite activities and multi-users in an ambient intelligent environment. In addition to that, there are also discussions on the benefit of activity recognition to the elderly, healthcare-related Activity Recognition (AR) and the technology supporting AR.