Basic word order
Basic word order refers to the sequence in which the subject (S), the object (O) and the verb (V) of a transitive sentence occur in speech. There are six possible orders: SOV, SVO, VSO, VOS, OVS and OSV. Of these, SOV and SVO are the most common, accounting together for about 80% of the world's languages. Most of the remaining languages have VSO word order, while VOS, OVS and OSV are rare.
Some languages are said to have free word order, i.e. all orders may occur. An example is Latin, in which the following six sentences are all equally correct (and mean the same, namely 'The dog bit the man'):
(1a) Canis hominem momordit.
(1b) Canis momordit hominem.
(1c) Momordit canis hominem.
(1d) Momordit hominem canis.
(1e) Hominem momordit canis.
(1f) Hominem canis momordit.
In Latin (and other free word order languages), any of these orders can be chosen for pragmatic (e.g., topicalization) or stylistic reasons (e.g., to make a verse scan and rhyme properly). However, there is usually one word order that is pragmatically neutral and found in most sentences of prose. (In Classical Latin, this order is SOV (example 1a), but it shifted to SVO in Vulgar Latin.)
Basic word order and noun phrase order
Noun phrases can be head-initial (the noun comes before its modifiers), head-final (the noun comes after its modifiers) or mixed (some modifiers precede the noun, others follow). Most SOV languages have head-final NPs, most VSO languages have head-initial NPs, while in SVO languages, both types, as well as mixed order, may occur, depending on the language.