Why I can't select the vertices of both my objects? I've created two objects (according to a tutorial) and I would want to select the upper vertices of the lower object and the lower vertices of the upper object in order to create a bridge between them but even though I can select both objects in Object mode (with Shift+LMB - only like this I can select them) only the first one selected can be modified. In the following picture I've selected both objects but only one can be modified:


What should I do in order to create the bridge between the two objects?
Blender only allows us to edit one object at a time (2.80 will add the ability to edit multiple objects). By having your mesh in different objects you need to edit them separately.

One option is to join the objects and edit them as one &#9096; CtrlJ. After you have finished you can separate them again if you wish with P and choosing by selection or loose parts.

Another option is to use snapping to align the verts of one object with the verts of another.