There has been an increasing trend in herd size in a number of countries which is associated with an increase in the number of cows per stock person. More specifically in the dairy cattle sector in Europe, since milk quota removal by EU in April 2015, many countries have implemented expansion programs mainly in the form of increasing cow milk yield and/or cow number. This expansion could result in less time and attention dedicated to each cow, which may eventually impact the health and reproductive status of the herd. Therefore, tools which aid reproductive management, especially those that are automated, are particularly valuable. Oestrus, commonly referred to as heat, is a behavioural sign and strategy to ensure that the female is mated close to the time of ovulation. Heat detection is vital for synchronisation protocols as well as breeding programs, more specifically artificial insemination and embryo transfer programs. There are a number of methods, techniques and tools currently available and being implemented for HD, some of which can be combined to improve the HD efficiency and accuracy. Visual observation involves a trained observer recognising and recording signs of heat with standing heat as the main behavioural sign of the oestrus phase. Electronic devices, particularly activity systems, have been widely introduced by different manufacturers in order to reduce the degree of dependence on visual HD. Recently developed pedometers are able to not only detect activity of cattle, but also the lying time and body temperature of the animal, thus increasing the specificity and sensitivity rate. Despite this improvement in specificity and sensitivity, almost all cattle units use these HD tools to aid but not replace the visual observation method.