About the Texts
Most online public domain versions of Shakespeare's texts are based on the Globe Edition of 1866, the Gutenberg Edition, or the MIT/Moby Edition (a revised version of the Globe Edition). There are many inconsistencies and errors in these editions so they are considered less-authoritative and poor for study. Alternatively, there are several quality editions of Shakespeare's works like the Riverside, Arden, and Bevington editions, which aren't free but come with a strong scholarly backing.
The PlayShakespeare.com team used the First Folio of 1623 (and Quartos where applicable) and the Globe Edition of 1866 as sources for the texts on this site. We've re-edited and updated these versions to reflect the editorial standards of the PlayShakespeare.com scholarly team, therefore you can rely on the quality and interpretive accuracy of the PlayShakespeare.com texts. A matrix of the editions used to compile the texts can be found here.
Additionally, PlayShakespeare.com is the only place to find Shakespeare's text with proper indentation, which preserves the meter. When reading and performing Shakespeare, it's important to us to see where characters have shared lines in order to preserve the rhythm of speech and the iambic pentameter.
As electronic editions of Shakespeare's plays proliferate, the need for "through line numbers" (Charlton Hinman's system from the Norton First Folio) vanishes due to the flexibility of systems for viewing and printing; not to mention the conflicts between the various editions of a single play (of which none are considered "correct") so they have been removed from our texts (there's a button to toggle them on and off). Therefore, the traditional method for actors and directors to find their place within a scene will more than suffice (act, scene, number of lines from beginning, etc.). If you really feel the need to have line numbers in your texts, most word processing programs can easily and automatically add the numbers for you.