This research paper presents a diachronic and comparative analysis of Old English and Modern English, focusing on three essential linguistic components, including: pronunciation, noun morphology, and vocabulary. Old English, spoken in England between the 5^th and 11^th centuries, represents an early and structurally complex stage of the English language.                 By examining these three elements, the study aims to illustrate both the continuity and the significant transformations that have occurred throughout the historical development of English. The analysis begins with pronunciation, highlighting the systematic nature of Old English phonology, including vowel length distinctions, the presence of diphthongs, and the use of consonantal symbols, including þ (thorn), ð (eth), and æ (ash), which are no longer part of Modern English orthography. These features are contrasted with the less phonologically transparent and more irregular pronunciation system of contemporary English. The paper further investigates noun morphology, emphasizing the inflectional richness of Old English nouns. Unlike Modern English, Old English nouns were marked for grammatical gender, number, and case, including nominative, accusative, genitive, and dative forms. Through examples of strong and weak declensions, the study demonstrates how grammatical relationships were encoded through morphological endings rather than word order. The gradual simplification of this system, particularly the loss of grammatical gender and case distinctions, is shown to be the defining characteristics of the transition from Old English to Modern English. Finally, the paper explores the vocabulary of Old English, which was predominantly Germanic in origin and relied heavily on internal word-formation processes, such as compounding, prefixation, and suffixation. This lexical system is compared with that of Modern English, whose vocabulary has been significantly expanded through extensive borrowing from French, Latin, and other languages. Despite these changes, the analysis reveals that a substantial portion of core Modern English vocabulary, especially terms related to everyday life, nature, and basic human experience, derives directly from Old English. Overall, this study demonstrates that while English has undergone profound phonological, grammatical, and lexical changes, Old English remains a fundamental element for the perfection of Modern English.