Photo below, courtesy: Malvin Foo of Ticket Mash.
Acoustic guitar's usually asociated with strumming, it's where the guitarist simply strum the guitar to accompany vocal. In the other hand, electric guitar asociated with band playing where the guitarist roles as lead or rhythm guitarist.
But guitar is actually an orchestral instrument like piano too. It can be played just by itself, solo guitar. The beauty of solo guitar is at the creativity to combine all the musical parts within 1 guitar, there's main melody, chords, bass line, percusive sound, and sometimes improvistation. It's like simulating the whole band in a guitar. I call it "playing band in the guitar".
The guitarist must optimally arrange the composition he/she delivers within all the technical & physical constrains he might face. He needs to know how to be the "singer", the rhtyhm player as "bassist", "keyboardist" & sometimes "percusionist". The use of "open string" is quite helpful when the guitarist plays very complex arrangement as he can just pluck the string without any requirement to press any frets.