Space piracy exists in a strange -- if somewhat amusing -- conceptual limbo: if most analysts agree on the fact that it does exist, very few can give a unified, consensual definition of it. While communal legal codes define notion such as "unlawful appropriation of cargo" or "craft hijacking", they do not have a clear concept of piracy in space.

One thing is certain, however. The stereotypical pirate, preying on cargo ships from their asteroid hideout, boarding innocent vessels, stealing their AI and plundering their riches does not exist in any realistic capacity. The very nature of geometry drive FTL travel makes interception an extremely complex affair and there is little economic case for such a practice of piracy, considering the risks of triggering an overwhelming response from the powers that be. It doesn't mean unlawful endeavours carried out with ships are unheard of.

A working definition of piracy could be elaborated by considering the three main elements that are required (yet not sufficient) for proper space pirates to exist:

• A lightly or un-policed space with enough of an economy to allow for valuables to be carried in and out of the system (said valuable can be goods, persons or information.)
• Organized groups or polities with the equipment, inclination and geographical presence to coerce civilian ships into giving in to their (often monetary) demands.
  
• A local context, be it political or ideological, that leads the would-be pirates to seek for subsistence and wealth through violent means. 
• A widely accepted -- regional or interstellar -- perception of the aforementioned actions as unlawful and falling under the definition of piracy. 

One may see an immediate problem with this definition: it is recursive. A pirate is first and foremost defined by the fact that the rest of human space sees them as such. This is the most crucial aspect of what it means to be a space pirate: perception. In regions like Smyrnia-Silesia or Tyra, there is a continuum between organized protection rackets and legitimate proto-states; many self-proclaimed Smyrnian pirates, like the infamous Solovyovan Recyclers, started as the former and ended up as the latter, transforming their racket into a system of trade taxes and organized fleets, often used to protect merchants against the racketeers they used to be. As the regions with rampant piracy also tend to be low-intensity warzones, some outside analysts tend to consider that piracy proper doesn't even exist, classifying all piracy-adjacent endeavours as military actions against civilian trade. It is not wholly nonsensical: in anarchic regions there is no such thing as a neutral merchant.