Since everybody is talking about modification nowadays, are you thinking that it might have to do with this.
Or does it refer to something else?
Actually these add ons are added features that you can make use of to enhance your gaming experience with the current version of that flight simulator software that you have.
Getting access to these add ons would not be a problem because most of them are provided free by software providers.
Most of the software providers nowadays have their own websites which aims to inform aircraft fanatics with certain updates regarding new software releases, added features that they can try and even free downloads to update their current software.
But before you go click on downloading a flight simulator add on, you have to make sure that what you are getting is the one that is compatible with your current aircraft software.
Since these simulators have different released versions, it is necessary for you to match your system requirements with whatever you are trying to install into your system even if these are just add ons.
Try browsing on the download details first before installing, running or downloading anything on your system.
Most of the add on features that may be available for you to update for your current software would include a more detailed mapping system, more detailed graphics and better sound system, allows having the right structure or facility if you would like to build a cockpit of your own, and a lot more detailed features to let you experience what real life flying is.
These flight simulator add on features may or may not be available for the current software that you have.
But is you are using the one that supports such enhancements then that would be better.
This would then allow you not only to enjoy playing with an aircraft game but at the same time learning and training yourself on how to actually navigate an aircraft of your choice.
With having the right simulator software at hand, you can ensure yourself that sim flying will not just be a game that you can play.
It can also give you enough experience to understand more about the things that a real pilot does, and makes you feel that you are a pilot yourself if you are not.