Defining crime is problematic because crime is a social construct and therefore heavily reliant on the context in which it is set. For example, the law changes with the times, meaning that acts which are considered criminal at one point in time are not necessarily considered criminal at another point. Culture is also relevant to how we define crime, and acts that are legal in one culture might be illegal in another. The age of responsibility also influences whether an act is considered criminal, and in the UK a child has to be at least 10 years old to be considered criminally responsible.