Tatwa Bodha of Adi Shankara is the basic text that vedantists start, so that many of the defenitions that Shankara uses is explained very lucidly and clearly. say for example. Maya is defined as ya ma' sa maya.-----THAT WHICH IS NOT REAL.does it mean it's unreal, no, it's not unreal. as you see it right in front of your eyes.it's apparent reality like my tee-shirt. tee shirt has a form and name. but ot depends upon the fibre which is satyam. hence fibre is the reality with respect to tee shirt. in the same way this jagat which you see is also maya, since it has name and form. but it depends upon conciousness which is the reality. hence that which is not real is maya.it's also called anirvachaneeya, that which cannot be explained in a single shot.that which you experience in this world is also maya only.