Grammaticality in linguistics is decided by the conformity to language usage corresponding to the grammar of a particular speech variety. The concept of grammaticality grew along with the theory of generative grammar, which aims to construct rules that define well-formed, grammatical, sentences. A grammaticality judgement is a speaker's assessment of the extent to which a linguistic string is well formed. It is based on whether the sentence is interpreted according to the rules and constraints of the relevant grammar. If the rules and constraints of the particular variety are followed, the sentence is considered to be grammatical. Linguists use grammaticality judgements to examine the syntactic structure of sentences. This book provides significant information of this discipline to help develop a good understanding of grammaticality judgements and related fields. It aims to give a general view of the different areas of this field, and its applications. The extensive content of this book provides the readers with a thorough understanding of the subject.