Praise & Worship is a genre of music, and the style of music generally played in church services around the world.
There are different schools of thought on what the difference between praise and worship are. However, a widely agreed upon definition is that "praise" is a song sung about God and "worship" is a song sung to God. Another belief is that worship is a way of life - our life should be in a constant state of worship towards our Heavenly Father - and praise is a part of that worship lifestyle. This stance does have scriptural support to back it up.