basic android file system I have a samsung galaxy 8, new to android from iphone 7. Since this system is new to me I wanted to get a rundown on the internal/sd storage files, where system files are stored, how to find apps and where they are stored. Basically I want to manage some files but I don't know the structure on the android system. Example: I want to store some lesser used icon packs to the external storage to free up some space. I don't know where to move them to, and what rules there may be for this. 
I also have alot of photo files which I want to store and use from the sd card.
If someone can please direct me to an article that would be really helpful.
You can download Es File Explorer App, click here to download it from Google Play Store. It makes easy to manage your files in Internal/External Storage, using this you can easily move your photos from Internal to External storage.

I hope this will help you.