Historically, the age of consent has varied throughout the world. In the UK in the 13th Century it was as low as 12. According to a University of Sydney report, Australian legislators claimed in the 19th Century that “white girls living in sub-tropical climates ‘ripened’ into women earlier than those in Europe," writes academic Stephen Robertson.
But since the early 20th Century, most countries throughout the world have raised the age to at least 16.
Still, the age of consent remains shockingly low in some countries - in Nigeria it is 11.
And in other lands it doesn’t exist at all. In some countries in Africa and the Middle East, such as Afghanistan, once a girl is married she is giving consent, no matter what her age.
In other countries, such as Argentina, the age of consent is 18.
In Europe it ranges from 14 in Germany and Italy, up to 18 in Turkey.
And in the US, it varies from state to state, from 16 in most states to 18 in California and Florida.
According to the AIFS, the four “areas of knowledge” when it comes to consent are: “Understanding of what the physical act(s) involve, their meaning, society's laws and cultural norms, and possible consequences.”
This includes the fact that the person should not be being tricked or fooled into engaging in a sexual act and that all parties should be freely giving consent – i.e. they are not intoxicated from alcohol or other substances (taken willingly or not).
Historically, age of consent has differed depending on whether the activity is between two people of the same sex. In Western Australia, the age of consent was once 21 for same-sex activity between males. It is now the same as for heterosexual sexual activity.
Despite the age of consent, there are still laws that prohibit an adult person from engaging in sexual activity with a child aged 16 and 17.
In New South Wales, Victoria, Western Australia, South Australia and the Northern Territory, it is an offence for a person to sexually engage with a person who is under their special care. A person providing "special care" is someone in a supervisory role such as a teacher, religious official, medical professional, employer or foster parent.
The punishments for engaging in sexual activity with a person under 16 are of course severe. In NSW, the maximum penalty of engaging in sexual activity with a child between the ages of 10 and 14 years - i.e. rape - is between 16 and 20 years' imprisonment.
But the act doesn’t always come under the umbrella of paedophilia. Sometimes the defence of the accused is that they believed on reasonable grounds that the person was above the legal age of consent.
Another defence relates to situations in which the two people are close in age. For example in Victoria and the Australian Capital Territory, if the accused is not more than two years older than the person who was under the legal age at the time of the sexual activity, then a defence of that nature can be put forward.
"Age of consent laws attempt to strike a balance between protecting children and young people from exploitation and other harms," states the AIFS, "and preserving their right to privacy and healthy sexual development."
Click here for a full list of age of consent throughout the word.