Crosslinked polymeric organic porous particles have a crosslinked organic solid phase and discrete pores dispersed within the crosslinked organic solid phase, which discrete pores are isolated from each other. The crosslinked organic porous particles are prepared using one or more water-in-oil emulsions containing a polyfunctional reactive compound and a reagent that causes crosslinking, and can be incorporated into or applied to various articles for many purposes. If marker materials are incorporated into the crosslinked organic porous particles, these marker materials can be detected using appropriate instruments.