What does the Constraint feature do in a SolidWorks sketch?

The Constraint feature in a SolidWorks sketch serves to restrict the degrees of freedom of the sketch entities. When constraints are applied, they define specific relationships and conditions that the sketch entities must adhere to, such as geometric relationships (like parallelism, perpendicularity, tangency) or dimensional relationships (such as fixed lengths and angles). This controlled environment helps ensure that the design intent is preserved as you modify the sketch or when dimensions are changed. By limiting the ways the sketch can be adjusted, constraints create a more predictable and manageable design process, enabling users to create robust and reliable models. This is an essential aspect of parametric design, where the relationships among dimensions and entities govern the overall shape and behavior of the 3D model.