A newbie: each time I slain a dragon, the bottom left hand corner of my shout screen indicate a number increase of souls. What perks does if offer as the number of soul rises ? thanks in advance!

you use the souls to 'unlock' the shouts you have discover. Until you use a soul to unlock the shout you will not be able to use them. Each time you unlock a shout it will use up a soul. I think the number you mean is simply the number of souls you have left to use. hope this helps.

They are used to unlock the words of power you learn from the walls to be used as shouts.

thanks that helps

evrytime you read a word wall and get a new shout you can't use it right away, but you need to unlock it with a dragon soul by pressing the corresponding button on the magic-->shouts menu.

Someone needs to create a mod that adds "Dragon Soul Gems" where you would need an empty one in your inventory to harvest the soul. Heck, even make it reusable, so you can only have one soul at a time. It's not like dragon souls are hard to come by!

Yup. I didn't realize this until I was about 100 hours in because the Greybeards give you the first couple for free.

They are obviously used to unlock Shouts...

The no. is the number of dragon shouts you have and also you can use them for unlocking shouts found on walls that give you words of power. The number you have can unlock new shouts and even though you find a shout you have to unlock it first to even use it. Hope this helped!

Collect enough of them to become a bad enough dude to save the president.

I don't think I took quite that long, but it did take me ages to work out why I couldn't use shouts I had selected after finding them on word walls.