In a set of engineering drawings, what lines represent the features that cannot be seen?

In engineering drawings, hidden lines are specifically used to represent features of an object that are not visible from the current viewpoint or perspective. These lines are typically drawn as dashed lines, indicating that the features lie behind the visible surfaces and cannot be seen in a typical frontal view of the object. This helps engineers and architects understand the internal structure or components that are essential for the design and construction process, even though they are not directly observable.

The use of hidden lines is critical for accurately conveying all relevant details in a design, ensuring that anyone who interprets the drawings understands both the visible and obscured features. This clarity is vital for effective communication among engineering teams, especially when discussing assembly, manufacturing, or installation processes.