With inspection for presence a product is examined for whether it is completely present. This mostly happens directly after an assembly step to remove incorrect parts from the production process or send it to a remachining place as fast as possible.
A presence check is a kind of completeness inspection. The product is complete, if the part which can be examined is present. Frequently a presence check is linked also with a position or location inspection.
With that in the following represented product a filter is introduced into the position planned for it. The left picture shows the complete product with existing filter. In the right picture the filter is missing and the product is removed from the production process.
product is complete
no filter available