What do the colors in a tajweed Quran mean?

What a tajweed Quran is

Tajweed means reciting the Quran correctly, the way it was taught by the Prophet ﷺ and handed down by teachers. Allah tells believers to "recite the Quran [properly] in a measured way" (Quran 73:4). A tajweed Quran puts those rules right on the page by colouring the letters they apply to, so you can see a rule while you read. See What is tajweed and do I need to learn it?

What the colours usually mean

Colour sets vary, but many editions use something like this:

• Grey: letters that are written but not pronounced, such as the silent alif or the lam in "al-" before certain letters.
• Red, orange or other warm shades: madd, a vowel that is stretched. Different shades show how long to hold it (2, 4 or 6 counts).
• Green: sounds made partly through the nose. This includes ghunnah (a nasal hum on noon and meem), ikhfa (softly hiding the noon sound) and idgham (merging one sound into the next).
• Blue: qalqalah, a slight echo or bounce on five letters (qaf, ta, ba, jim and dal) when they have no vowel.

Some editions use extra colours for heavy letters or for the noon changing to a meem sound before the letter ba (iqlab). That is why the key at the front of your copy matters. See How do I learn to read the Quran in Arabic as an adult?

How to use the colours

• Learn to read the Arabic letters first. The colours help only when you can already read the words.
• Learn one colour at a time, starting with madd (stretching), then ghunnah.
• Listen to a good reciter while following the colours, so you hear what each one sounds like.
• Have a teacher check you. Colours show which rule applies, but a teacher corrects how it sounds.

Remember the colours are an aid

The colours are a modern learning tool; they are not part of the Quran, and you can recite perfectly well from a plain copy. Anas described how the Prophet ﷺ recited with "the prolongation of certain sounds" (Sahih al-Bukhari 5046), which is exactly the kind of detail the colours point to. If you're slow, don't worry: the one who finds recitation hard receives a double reward (Sahih Muslim 798). See What kind of Quran should I buy as a new Muslim?