Template:Modeling polygons booleans

Boolean operations can be performed on 2 overlapping polygon objects. Select both objects and go to Mesh > Booleans >

There are 3 options:

union

you keep the part of the objects that is part of one or both of the objects

difference

you keep the part of the object first selected that doesn't overlap with the object that has been selected second

intersection

you keep the part of both objects that overlaps

When you're using the union or the intersect option it doesn't matter in which order you select the objects. For the difference option, the second object you select will be subtracted from the first object you select.

When you're using the difference option it's possible you want to make a lot of holes in the object, like in the example below. It will be rather time-consuming to do them all one at a time and sometimes the geometry does odd things when doing it that way. So if you want to subtract these shapes all in once, you have to combine them first (select all the objects you want to subtract, then go to: mesh > combine). Now select the object you want to subtract from, then select the combined objects you want to subtract, then go to Mesh > Booleans > difference: