Holi, like most other Indian festivals, celebrates the triumph of good over evil. However, this two-day festival takes on other meanings as well. It is the signifier of spring, new beginnings, and love. Holi begins on the first full moon that falls between February and March—this year, on the 1st.
The word Holi is derived from the name 'Holika,' the evil sister of an even greater evil demon king, Hiranyakashipu. After the king had performed years of rites and penance, he was granted a boon by the creator, Lord Brahma (one of three gods of the Hindu trinity), who yielded him five special powers. He couldn't be killed by a human nor animal, neither during the day nor night, neither indoors nor outdoors, neither by projectile nor handheld weapons, and neither on land nor in water or air.
The king thought he had been granted immortality and demanded everyone worship him as a god, or they would be killed. His son Prahlada knew this was wrong, and as the killings began and grew in numbers, he began to pray to Lord Vishnu (the sustainer) to end the madness.
His father took great offense to this, and even began to plot ways to kill his own son. After many failed attempts, he called upon his sister Holika, who tricked Prahlada into stepping into a bonfire with her while she had a magic cloak on to shield her from the flames. The cloak flew from her back and onto him, saving his life.
Finally, Vishnu appeared from the flames reincarnated in a half-lion, half-human form at dusk on the verandah of the palace. He grabbed the demon king and clawed him to death. The five criteria regarding his boon had been avoided. And so, during the first night of Holi, bonfires are burned to symbolize the death of evil (Holika and Hiranyakashipu) and the return of good.
The second day of Holi takes on a different mythological significance. It is the commemoration of the divine love shared between Radha and Krishna; color, caste, and creed are cast aside, and all are welcomed. This is why color is an integral part of the festival. Not only does it highlight spring and the flowering of trees, but it also signifies a togetherness. It doesn't matter who you are—everyone is one smeared with red, pink, yellow, etc.
This is why I personally don't care who celebrates Holi regardless of their religion as long as they understand the sentiment and significance of the festival. Its meanings carry beauty that are lost if one is ignorant to them. But, overall, it's a coming together of all people with love, fun, and frolic. Happy Holi!