The connection tool draws a connection dot.
It indicates that wires are connected to each
other e.g. wires that cross at right angles can be connected together
by placing a connection at the junction. The the netlister will
connect these two wires together producing a single net.
The connection dot also breaks wires as part of the connection
algorithm - this has a useful side effect - which is to split wires at
the connection point. For a horizontal wire, if one end is
dragged vertically then a new vertical wire is created at the
connection point. See diagrams below.
This feature is useful for moving parts that have lots of parallel wires attached to them as without placing connections wires can overlap on a move:
The procedure is to apply connections to the parallel wires in a
line - then when the part is moved no wires overlap.
The size of the connection dot is controlled from Edit-->Options-->Schematic.