The primary colors in the RGB color model are Red, Green, and Blue. Yellow is a secondary color, which can be created by mixing Red and Green.

A gradient is a gradual change in color or tone from one area to another. It is often used to create smooth transitions between colors or to add depth and dimension to an image.

Specular light is not a type of light source commonly used in digital art. It is a type of reflection that occurs when light hits a shiny surface and is reflected in a specific direction.

Shadows are the darkest areas of an image, where light is completely blocked. They are often used to create depth and dimension, and to add a sense of realism to an image.

Impressionism is not a common rendering style used in digital art. It is a style of painting that originated in the late 19th century, characterized by short, thick brushstrokes and a focus on capturing the overall impression of a scene rather than the details.

Value is the term used to describe the overall brightness or darkness of an image. It is one of the three main properties of color, along with hue and saturation.

The Smudge Tool is not a common technique used to create highlights in digital art. It is a tool that is used to blend and smear colors together, and is often used to create soft edges or to add texture to an image.

Shading is the process of adding light and shadow to an image to create a sense of depth and realism. It involves defining the light source and direction, and then applying shadows and highlights to the objects in the image.

Ambient shadow is not a common type of shadow used in digital art. It is a type of shadow that is caused by the overall ambient light in a scene, and is not associated with a specific light source.

Color grading is the process of adjusting the colors in an image to achieve a desired look or mood. It involves adjusting the hue, saturation, and brightness of the colors in the image, as well as adding or removing color casts.

Rim light is not a common type of light used in digital art. It is a type of light that is used to create a thin, bright outline around an object, and is often used to add depth and separation to an image.

Blending is the process of creating a smooth transition between two colors or tones. It involves using a variety of techniques, such as the Gradient Tool, the Smudge Tool, and the Blur Tool, to create a seamless transition between the colors.

Vector graphics is not a common type of rendering engine used in digital art software. It is a type of graphics that is based on mathematical equations, and is often used for creating logos, illustrations, and other types of graphic design.

Texturing is the process of adding texture to an image to create a sense of realism. It involves applying a texture map to the surface of an object, which defines the color, roughness, and other properties of the surface.

The Smudge Brush is not a common type of brush used in digital art software. It is a tool that is used to blend and smear colors together, and is often used to create soft edges or to add texture to an image.