I don't know much about Instantons, and looking through the Wiki page it seems like one must have a lot of knowledge about QFT to understand them. However recently I've encountered a statement (which I cannot refer to or extract more information) that instantons are "-1 dimensional" objects in the context of string theory.
The explanation is that if a 0-dimensional object (pointlike-particle) creates 1D worldline the spacetime, the 1-dimensional object (string) creates 2D worldsheet in the spacetime, instanton can create 0D-event(s) in spacetime.
How can it be a -1 dimensional object? Can you explain it in more details?
Are there any materials about instantons (which deals with some simple technical aspects) you can present?