I'm someone who has been working in several different fields since a decade, such as BPO, Accounting and lately going into programming. I have always admired music through numerous songs throughout my life so far. I always had this thing that I want to be able to play atleast one instrument in my life. So last week I bought a guitar. But I have no sense of what goes behind making the songs. So I decided to learn the basics of music theory and I got to know what notes, sharps and flats are. Little bit about triads and diatonic chords.
But what I don't understand is the chord shapes or the CAGED shapes. Can someone explain how those are made/drawn? There must be some logical explanation for them. Like how it's determined that a certain string are to be muted, certain to be played open. Taking A major chord's instance, how has it been decided that the 6th string will be muted, 1st and 5th strings to be played open and why the E, A and C# are played on the 2nd fret while there are other many frets that have those notes, why only the 2nd one? I have no problem with their design or something but I want to understand how they came into picture the way they are. Please help as I'm overwhelmed by the chord shapes.