There can be many possible reasons why your guitar isn't playing or sounding as good as it could be. A regular guitar setup can help with this, and central to that is something called intonation.
When an electric guitar is properly intonated, every note on the fretboard will sound in its correct pitch. And the clearest way to know that your guitar isn't intonated correctly is it never sounds properly in tune as you play certain notes, even if you've just tuned it. Then tuned it again.
