I'm starting with svg files in my websites and I'm really wondering when to use the svg code or the svg image.

i.g. 
When I save a file from Illustrator as svg I have two options I can use both.
I can save the image and I can export to code.

But when do I use what? Is is smarter to use the image in my website or do I use the code. With all the current knowledge I have I should use the code because that is way lighter (kb's). Or should I use the image as a fallback?

I have no idea... I hope somebody can shine some light in to the darkness

M.