The Pirc is named after Vasja Pirc, whose advocacy helped popularise the defence in the twentieth century. Earlier examples of similar play existed, but the opening gained wider recognition as players became more comfortable challenging a centre after allowing it to form. The related Modern Defence shares the kingside fianchetto idea while often delaying ...Nf6.
That knight move is an important distinction. In the Pirc, ...Nf6 attacks e4 and encourages White to decide how to support the centre. A Modern move order beginning with ...g6 can leave that question open for longer. The systems can transpose, but White may use the difference to choose a different setup or gain space before Black commits.
The diagram shows White occupying d4 and e4 while Black prepares ...Bg7. Black must eventually challenge the centre, commonly with ...c5 or ...e5, under suitable circumstances. White can develop calmly or build a more ambitious pawn front, as in the Austrian Attack. Allowing space is only workable if Black knows how to undermine it.
Practise the Classical System first and identify where Black's central break becomes possible. Then examine the Austrian Attack to see how White's extra ambition changes the calculation. Treat the shared fianchetto as the beginning of the study, not a complete plan. The historical development of these defences reflects a practical question: when can pressure against a centre compensate for allowing it to grow?
Try this at the board
Compare the shown Pirc position with a move order that delays ...Nf6. What immediate attack on e4 is missing?