In linguistics grammaticality is determined by how well a sentence conforms to the language usage corresponding to the grammar of a specific speech variety. The concept of grammaticality evolved in tandem with the theory of generative grammar, which seeks to formulate rules defining well-formed, grammatical sentences. A speaker's evaluation of the degree to which a linguistic string is well-formed is the basis of grammaticality judgment. This assessment is contingent upon whether the sentence aligns with the rules and constraints of the pertinent grammar. Linguists utilize grammaticality judgments to analyze the syntactic structure of sentences, considering them grammatical if they adhere to the rules and constraints of the particular variety in question. This book provides significant information of this discipline to help develop a good understanding of grammaticality judgements and related fields. It unfolds the innovative aspects of this area which will be crucial for the holistic understanding of the subject matter. This textbook, with its detailed analyses and data, will prove immensely beneficial to students involved in this area at various levels.