A privilege and an obligation of the Christian where we communicate with God. It is how we convey our confession (1 John 1:9), requests (1 Tim. 2:1-3), intercessions (James 5:15), thanksgiving (Phil. 4:6), etc., to our holy God. We are commanded to pray (1 Thess. 5:17).
Some personal requirements of prayer are a pure heart (Psalm 66:18), belief in Christ (John 14:12-14), and that the prayer be according to God's will (1 John 5:14). We can pray standing (Neh. 9:5), kneeling (Ezra 9:5), sitting (1 Chron. 17:16-27), bowing (Exodus 34:8), and with lifted hands (1 Tim. 2:8).