Patio is an outdoor area that is used for relaxing and having friends round for that BBQ.
Patios are usually made of concrete or, the more popular, stone slabs laid over a firm base and often these days they extend onto the ever popular decking, these are an extension of the traditional patio and BBQ area and are made from wood and can be used in other ways too such as an extension to living areas of houses and also as an alternative to stone based features.
Patio is from the Spanish meaning back garden or backyard.
A good base is required to form a layer of compacted hardcore, a layer of sharp sand, and a layer of cement, if you dont prepare correctly and have a good firm base for your patio and BBQ area, you will most lickely end up with cracked slabs.