Intersex is a state is which an organism does not fix the criteria to be classified as strictly male or female. This may be due to one's sex chromosomes, gonads, genitalia, hormones, and/or secondary sex characteristics varying from what is traditionally thought of as biologically male or female. An intersex organism may have biological characteristics of both the male and female sexes. Intersexuality is observed in many animals including humans.
According to the ISNA definition, 1% of births exhibit some degree of sexual ambiguity. Between 0.1% and 0.2% of live births are ambiguous enough to be the subject of specialist medical attention, such as surgery to disguise their sexual ambiguity. Although, the number of person who are intersex cannot truly be known, as some chromosomal conditions do not make themselves obvious, meaning some people can go most, if not their whole lives not realizing they're intersex.
It's important to note that intersex is not related to being transgender. Transgender individuals identify as a gender other than the one assigned at birth, while their body may still be completely biologically male or female. Intersexuality is caused by genetic mutations, which result in someone being physically not completely male or female. Although some intersex people may identify as transgender or non-binary not all do.
The intersex flag was created by Intersex Human Rights Australia (IHRA) in July 2013. Yellow and purple were chosen for being 'hermaphrodite' colors, being neither blue or pink. They describe the circle as being 'unbroken and unornamented, symbolizing wholeness and completeness, and our potentialities. We are still fighting for bodily autonomy and genital integrity, and this symbolizes the right to be who and how we want to be.'
There is an alternate intersex flag made by Natalie Phox in 2009. However the flag was originally titled as the bigender flag but was later changed, causing confusion, and making it unclear who the flag was suppose to be for. The yellow and purple one is more widely used for these reasons.