By put-call-parity, a long call plus a short put at the same strike replicates the stock. delta is about 1.00, gamma, theta and vega roughly cancel, and the P&L line is a straight 45 degrees.
Traders use it to get stock exposure with less cash outlay, to take a position in a hard-to-borrow name, or to keep exposure while shares are tied up elsewhere. The catch is that the short put carries full downside and full early-assignment risk.
Example: XYZ at $50. Buy the $50 call for $2.30, sell the $50 put for $2.10, net debit $0.20 or $20 per contract. If XYZ goes to $56 you make roughly $600 − $20. If it goes to $44 you lose roughly $600 + $20. Exactly like 100 shares, for $20 of cash instead of $5,000 — plus a large buying-power-reduction.
Related: synthetic-short-stock, put-call-parity, conversion