The rainbow flag that has turned out to be a worldwide icon of hope for LGBTQ individuals around the world, first flew in San Francisco bay area’s United Nations Plaza for Gay Pride Day, on June 25, 1978.

It had eight colors — two more than today’s version — and was created by Gilbert Baker, an openly gay artist, and activist. He has previously been accredited to develop an icon for the LGBTQ people by his associate Harvey Milk, the initial openly gay chosen official in California.

Baker drew motivation from the US national flag, which had commemorated its bicentennial in 1976, and a real rainbow, which showcases the colors of the light spectrum in approximately precisely the same sequence since the flag. He assigned a meaning to every one of this colors: hot pink for sex, red for life, orange for healing, yellow for sunlight, green for nature, turquoise for magic, blue for harmony and violet for spirit.

The first flag measured 30 by 60 feet and Baker, who was then 27 yrs. old, had sewn it by hand.

Reference
Pride flag: A history of the Gilbert Baker rainbow design …. https://www.cnn.com/style/article/pride-rainbow-flag-design-history/index.html