[wdreamsmaycome]

I am a total newcomer to the guitar world, and I am having trouble understanding the lesson tabs.

Take blackbird for example, I understand that in the tab(s) the number represents the fret the string is fingered at, and that strings with no numbers are not supposed to be played, however I can't figure out the following:

= why are some numbers linked by vertical bars? Does that mean a barre' chord?

= what are the vertical tabs above the "normal" tab? Take the first and last in blackbird again, they both say they are a G chord, however they are quite different, and, especially in the first G, different from the chord written out in the horizontal tab.

= is there any way to figure out from the tab which strings are picked when or is that something left to the player?

Sorry if my question might appear obvious to you, but I am really not used to tabs yet (coming from a piano/organ background).