Prioritization is the process of ranking species, pathways, or sites for the purposes of:
- determining their relative environmental (and sometimes also socio-economic) impacts, and
- for deciding on the relative priority of actions to effectively and efficiently prevent or mitigate the impact of invasive alien species 
Priority species, pathways, or sites are therefore those that are identified as posing the greatest risk to the environment and biodiversity and, in some cases, also the greatest opportunities for preventing such risk. 
A prioritization scheme (or prioritization model) is any structured system that produces a ranking or ordered set of risk categories. 
The figure below (see also ) shows that the process of prioritization in biological invasion happens for two distinct purposes, including risk assessment (RA), and both purposes can be addressed as part of the same process. Existing prioritization schemes vary widely in the relative emphasis given to one or both of these purposes (from ).
Referenced material and links
McGeoch, M.A., Genovesi, P., Bellingham, P.J., Costello, M.J., McGrannachan, C. & Sheppard, A. 2016. Prioritizing species, pathways, and sites to achieve conservation targets for biological invasion. Biological Invasions 18, 299-314. doi 10.1007/s10530-015-1013-1