The project, which compared languages with articles and languages without articles, involved several subdisciplines of linguistics, in particular syntax, semantics, and typology. With a few exceptions, it was standardly assumed before this project that languages without a definite article have a phonologically null (i.e. unpronounced) definite article, which means that the difference between languages with a definite article and languages without a definite article is merely a matter of pronunciation, i.e. phonology. In contrast to this view, the project has shown that there are radical differences in both the structure and the interpretation of both the nominal domain and the clausal domain between languages that have a definite article and languages that lack a definite article. This was done by establishing more than twenty wide ranging crosslinguistic generalizations where languages differ with respect to a number of syntactic and semantic phenomena depending on whether or not they have a definite article. These generalizations concern phenomena as different as the availability of free word order in a language, the locality of syntactic dependencies, and the interpretation of tense, negation, and superlatives, to mention just a few, all of which have been shown to be crucially affected by the presence vs absence of a definite article in a language. The project has thus shown that whether or not a language has a definite article has a fundamental impact on a number of syntactic and semantic phenomena that were previously considered to be completely unrelated. In fact, it is fair to say that very few properties of human languages have such a profound impact on the complex system of the human language grammar as the lack vs presence of a definite article in a language. In addition to establishing a new typological division, and contributing to our understanding of the syntax and semantics of a number of linguistic phenomena, the project has significant consequences for the hotly debated issue regarding what kind of syntactic and semantic variation can be found in human languages. The project has investigated more than one hundred languages. It has also involved investigation and data collection on languages that have not been well-studied, enhancing our understanding of the structure and the interpretation of a number of constructions in these languages. The project thus also has considerable descriptive value. Given that the lack vs presence of a definite article in a language has a crucial effect on a number of superficially unrelated syntactic and semantic phenomena, reducing the superficial complexity in this domain to a single determining factor, the findings of the project are expected to have consequences for the studies of language acquisition within both psychology and linguistics, which have to explain how children acquire the phenomena in question. The findings of the project are also expected to have consequences for the studies of language acquisition regarding the more narrow question why definite article is typically absent in early child speech as well as for the studies of aphasia regarding the absence of definite article in the speech of some aphasics.