Hello there,
I have some trouble wrapping my head around what joining does in Blender. Linking means changing the structure of object a will do the same to the linked object b from what I gathered. But what exactly happens if you join them? In the video they were still separated spatially, and there was no connection anymore when you changed one of the structures (=no linking), so what exactly is the connection you get from joining objects? My idea was that they could be treated as one single shape or object, but clearly that wasnt the case as you could still individually work on the structure. I tried googling it, but it seems like everyone already knows what it is and they’re just trying to find out how to do it 
You were on the correct path.
First, In blender linking two or more objects means that they all become duplicates of one another. That is each of the objects use the exact same data to define their mesh.
Joining on the other hands takes multiple objects and turns them into one object. In much the same way that your keyboard is a single object. While it is true that you can work on the separate parts of that object individually, they are in fact one object. And of course, if you want it to be a single part then you can create faces and edges or just remove doubles.
Joining is more like technical aspect:
- you can only have one origin point per object. ( individual origins in edit mode doesn’t counts as origins only exist at the time of moving)
- You can only edit one object at a time. (mirror modifier and linked objects doesn’t counts as it is isn’t actual editing.)
- seperated objects are not connected with faces/edges.
- Modifiers are applied to a whole object only.
Separating/joining is basically just the way of telling Blender that those objects are different objects. That is required for a lot of operations.
You will find out more as you do stuff and move through the course.
Thank you both for your reply
I’m actually still not sure if I understand more now, but maybe just going on and see what else is coming might be the best course of action. I’m still trying to figure out what the hard part for me to understand is in order to ask a better question… I think what confused me in the video was that the joined object was in two unconnected parts - can one object be separated like this?
can one object be separated
Surely. But separate objects can’t be connected on the other hand, they can be very closely, even protrude into one another, but they can’t have edges and faces that are joined to both objects.
I think you can try thinking of joining as moving the mesh of object1 into the space of the object 2. like say 2 people initially leaving in separate house, but then person1 moves into the house of person 2. so now those 2 poeple can share resources that belong to the house.
in terms of what it means to blender it means that you can edit the 2 separate objects in edit mode now, whereas separate objects can only be edited one at a time.
you can do this experiment that demonstrates: in object mode, add a cube to the already existing one. now select only 1 of them, then enter edit mode. Now while in edit mode, try to select the other cube, you will not be able to… if you type “a” which is select all, it will only select the cube you entered select mode with.
now if you get out, select both cubes and join them, first you will see that when you deselect them and re-select one cube, both will be highlighted as the same object… at this point is not like you have two cubes… it’s that you have 1 object with 2 cubes in it… now enter edit mode and you’ll see that now both cubes can be selected or edited.
You might think of it in terms of one of these:
A binder is considered a single object by most people I’ve ever met.however, the reality is fare different
Open the rings and you will quickly discover that a bindert is made of 100’s of different pieces. and each one can be modified or removed (or new ones added) without changing the fact that it is a binder. In the same way, joining one or more parts into a single object doesn’t change the object (or the parts themselves) but it does make it easier to work with.
Thank you guys for taking the time to explain it to me
I think I got it now!