In Computer-Aided Design (CAD), an extrude is a modeling operation that creates a 3D shape by extending a 2D profile along a straight path. Extrusion is one of the most basic and commonly used features in CAD, allowing designers to quickly create solid geometry from simple sketches.

To create an extrude feature, designers first create a 2D profile or cross-section, typically using sketch tools such as lines, arcs, and splines. The profile defines the shape of the base of the extrusion, and can be closed or open, depending on the desired result.

Once the profile is created, designers specify the extrusion parameters, such as the distance and direction of the extrusion, the taper angle, and any draft or offset distances. The software then generates the 3D solid by extending the profile along the specified path, creating a solid volume.

Extrudes can be used to create a wide variety of shapes and features, such as:

1. Simple shapes: Boxes, cylinders, prisms, and other basic geometric shapes can be easily created using extrudes.

2. Bosses and ribs: Extrudes can be used to create protruding features on a model, such as mounting bosses or reinforcing ribs.

3. Cuts and pockets: By extruding a profile in the opposite direction, designers can create cuts, pockets, or cavities in a model.

4. Text and logos: Extrudes can be used to create raised or embossed text or logos on a model, by extruding a sketch of the desired shape.

Extrudes are a fundamental tool in parametric modeling, where the geometry of a model is defined by parameters and relationships. By creating an extrude feature from a parametric sketch, designers can easily modify and update the model by changing the dimensions and constraints of the sketch, without having to recreate the entire feature.

Most CAD software packages provide a range of tools and options for creating and editing extrude features, including different end conditions (such as blind, through-all, or up-to-surface), direction options (such as one-direction, symmetric, or mid-plane), and merge options (such as join, intersect, or cut).

By mastering the use of extrude features, designers can quickly and easily create complex models from simple sketches, and can explore different design variations and iterations with ease.