Rosette Nebula

Diffuse nebulae
The diffuse nebulae near the stars are examples of reflection nebula.
Most nebulae can be described as diffuse nebulae, which means that they are extended and contain no well-defined boundaries. In visible light these nebulae may be divided into emission nebulae and reflection nebulae, a classification that depends on how the light we see is created. Emission nebulae contain ionized gas (mostly ionized hydrogen) that produces spectral line emission. These emission nebulae are often called HII regions; the term "HII" is used in professional astronomy to refer to ionized hydrogen. In contrast to emission nebulae, reflection nebulae do not produce significant amounts of visible light by themselves but instead reflect light from nearby stars.