Red, found in rainbows, possesses the longest wavelength of light (620 to 740 nanometers). It is the second most popular favorite color among humans (the first is blue) and is found on more than 75% of all the world's national flags. Red is the first pigment ever used for art.
Traffic lights and signs globally contain red to denote a stop is needed while traveling in a particular direction. It is one of only four colors that are part of the name of a Sea (the others being the Black Sea, White Sea and Yellow Sea).
Reddish dyes can be produced from vegetables, the bodies of certain insects, and from minerals such as iron oxide. Ancient Aztecs treated dyes in this coloration as more valuable as gold or silver, as it took hundreds of people to collect the female cochineal beetle from which it was made.
Appearances of the color red
Red (or its variations), in the King James Bible, is found 59 times. There are several Hebrew Old Testament words translated as it. The most frequently used words are adom (Strong's Concordance #H122), which is the color's name, chakliyl (#H2447), which literally is 'dark' or a person stimulated by wine, suph (#H5488 and #H5489), which is 'a reed' and is used to refer to the Red Sea, and adam (#H119), which means to show blood.
In the New Testament, the Greek words used are purrhazo (#G4449), which refers to the color's name, eruthros (#G2063), which is used to refer to a sea, and purrhos (#G4450), which references something that is the shade of fire or flame.
Its use in the Bible lends itself to symbolically representing sin and sinfulness (Isaiah 1:18), Godly vengeance against sinners (Psalm 75:8, Isaiah 63:2) and bloodshed along with war (2Kings 3:22, Nahum 2:3, Zechariah 1:8, 6:2, Revelation 6:4, 12:3). It can also carry the meaning of being tempted to sin (Proverbs 23:31).
Three prophetic animals
God commanded ancient Israel to use the ashes of a red heifer for the ceremonial cleansing of the tabernacle in the wilderness (Number 19:3 - 6). The New Testament seems to indicate that some sort of altar or temple (with sacrifices?) in Jerusalem will exist in the End Time before the return of Christ (Mark 13:14, Matthew 24:15, 2Thessalonians 2:3 - 4).
Some Christians and orthodox Jews would like to see a third temple built in Jerusalem. If and when such a building is erected, however, the belief is it would first need cleansing by the ashes of this special heifer before it could be used.
The horse of Revelation 6, symbolizing war and bloodshed, appears when one of the prophetic end time seals is opened (Revelation 6:1).
The appearance of the great red dragon of Revelation 12, representing the power of Satan and his steadfastness to bring bloodshed and death to all, signals the beginning of the worst time any human will experience (Matthew 24:21).
Added info on Biblical meaning of red
The Red Sea is a body of water that lies between the African continent (modern Egypt, Sudan, Eritrea, and Djibouti) and the Arabian Peninsula (Saudi Arabia and Yemen). Its length is about 1,400 miles, with a maximum width of about 220 miles, and is the most northern sea on the planet that is tropical. It is unusual in that no rivers flow into it.
Egypt's Pharaoh was angry and foolish enough to chase the fleeing Israelites as they miraculously crossed the Sea dry shod. When the last Israelite made it to the other side of the sea, God caused its waters to return to normal, thus drowning Pharaoh's entire army (Exodus 14 and 15).