When i rename artists/songs' info in itunes library, does this permanently rename them on the harddrive?

for example, i have tons of music and many of them are not titled, so when i manually put in info myself about the artist/song in itunes... it looks like it changes it on my external harddrive as well. i want to make sure that this is exactly what it does... so even when i unplug my external harddrive or even delete my whole itunes library, that it's permanently saved on my external harddrive just the way i typed it in on itunes, this is so i won't have to go through the whole process again of typing in the info when i bring my music up in the itunes library again

right now, because i'm not so sure, i have been typing in the info in the blank spaces or replacing correct info in itunes, then i highlight it, copy it and paste it in one of my folders on my external so it's saved like that (but then this also ends up with duplicates on my external, so then i have to delete the original, and keep the copy)... then i bring up the song file again (the copy one) up in itunes that has all the info (if this makes any sense)... this seems like double the work though... when i can just do it once and it's saved automatically and permanently

i've looked through the internet about this but i haven't found any straight forward answers of what i'm asking and looking for, please help