"" />
Im not much into theory but i started to read and learn a few weeks ago just basics and i think this is a thing i must understand.

Lets say someone says "This song is played in G" why is it helpful too know what the song is played in? I think it is if you wanna solo over it and want to solo it right. But then G Blues Scale and there is some Bebop scale or what its called, if you play that in G to the song does it work too, is it "right"? There is different notes in both scales.

Im not good in english but i hope you understand me.
you could try it. Might work, might not.

but it's important, because if you're gonna jam to a song in G and you play a lick in Eb it's gonna sound like uber****

Do not over think it- that is my best advice.

If I told you that this song is in B flat.. then I am giving you a generalization... just in case you get lost you can improv, or just solo. Because in anything you play there will be "accidentals" which is a note outside of the scale.

Unless the specify which scale to play (like "this song is in B flat minor") you should play the major.. With a bit of training you'll be able to hear the difference in the scales (major sounds brighter, minor feels sad and incomplete)

But again.. It is just a generalization. In the 9 years I've spent doing classical music, I have not played a song where an accidental was not written in. So give it a try.. but just remember not to go too far with it.
He don't remember, how it got there
It had a number, written on his forearm
It spelled disaster