There are things in the game that will appear after you fight in Runescape. These are called “splats” and are colors that will appear on your character. There are four colors, only two of which you’ll see in a free member game. The color of these "splats" will tell you the damage you’ve received.
There is a blue splat that means you’ve not received damage, which is always a good one to see. This one basically says that you dealt all the combat in the fight, and that they have not lowered your hp any. There are green splats that show poison damage. You can drink some anti-poison potion to get rid of this. Red splats tell you the amount of damage that was given to you on the last hit of the attack. The last color, gold, will tell you that you are diseased. Your hp won’t be affected but a stat will be. These can be dealt with by taking a Relicym’s Balm.