Looking at a picture of a nebula gives me a "feel-good" attitude. The colors and the lights does not fail to amaze anyone. These are huge collection of gases that can be found between the vastness of space. Ancient astronomers took notice of these cloud-like features and called them Nebulae from the Latin word for clouds. Most of them are light years across and is thousands of times larger than our solar system. Some of them are birthplaces of stars. And some of them are remnants of stars that died out and emitted vast amounts of gases and different elements that we already know. The plural form is actually Nebulae though some use "nebulas".
These are categorized as Dark Nebulae, Emission Nebulae and Planetary Nebulae. Dark Nebulae are simply the dark clouds that obscure light from other gases.
Emission nebulae are simply the glowing ones,. they appear bright against the black backdrop of space.
Red Emission Nebula
Planetary Nebula are called as such because most of the time they resemble a shape of a planet. They have stars in their centers and eventually the gas expands or form into planets, asteroids, moons and comets.
Cat's Eye Nebula
The picture below created by an astronomy fan, has some interesting facts too about some nebulae.
Here are other nebulas. For now no need to remember names just feel their majesty. Cheers!
Resource: McGraw-Hill: Astronomy Demystified. p338-339