Here are some definitions of Universal grammar on the Web: * Universal grammar is a theory of linguistics postulating principles of grammar shared by all languages, thought to be innate to humans (linguistic ... en.wikipedia.org/wiki/Universal_grammar * Sometimes Universal Grammar refers simply to the aspects of language that all languages have in common. ... homepage.ntlworld.com/vivian.c/Linguistics/LinguisticsGlossary.htm * "A grammar specifiying the possible forms a language's grammar can take." (C: 432) Chomsky's universal grammar consists of a set ... www.ling.ohio-state.edu/~jpcl/glosys-z.htm * Chomsky's hypothesis of a single grammatical system which is transmitted genetically and accounts for the ability of all normal humans to ... www.csa.com/discoveryguides/lang/gloss.php * A set of general principles that apply to all languages, rather than a set of particular rules. www.finchpark.com/courses/glossary.htm

well, these are a few, few examples, the subject is not easy and not possible to tell in few lines. One thing you should be aware of is if you intend to speak about psicolinguistics or computacional linguistics. the approach is not the same. Whatever it may seem after these words, i am not an specialist or alike. the fact is that i like psicolinguistics a lot and read some things. Anyway, i suggest you to look for something called "universals in languages". it's easier, funnier, and people listening to you will think you are a very clever person.( of course if you are not at university)