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Video abstract for the article 'A coupled lossy local-mode theory description of a plasmonic tip' by J Barthes, G Colas des Francs, A Bouhelier and A Dereux (J Barthes et al 2012 New J. Phys. 14 083041). Read the full article in New Journal of Physics at http://iopscience.iop.org/1367-2630/14/8/083041/article. GENERAL SCIENTIFIC SUMMARY Introduction and background. Light superfocusing has attracted considerable attention for applications ranging from highly sensitive spectroscopies, nano-object manipulation (nano-optical trap) or light addressing at the nanoscale. In this context, plasmonic tips provide an efficient way to convert an optical guided mode to a plasmon confined at the tip apex (see figure). Such a configuration allows powerful manipulation of light at the nanoscale. In order to understand and optimize the conversion mechanism along the plasmonic tip, we have adapted the coupled local mode theory to account for losses that are inherent to plasmonics systems. Main results. The coupled local mode theory describes the field propagation in slowly varying optical waveguides. To this end, the field is approximated by a superposition of the local modes supported on a given cross-section. This provides a clear understanding of the conversion mechanism from input to output mode but is generally limited to non-absorbing systems. In this paper, we extend this theory to lossy local modes and apply it to a plasmonic tip. We clearly identify the pertinent parameters and coupling regimes that govern the light propagation. Wider implications. We expect various implications beyond plasmonic tip designing. Indeed, the coupled lossy local mode theory is general and could find applications in investigating, for example, tapered waveguides and coupler or near-field optical probes. Particularly, the role of leaky (and to some extent, radiation) modes could be included.