Noun Declension: Old English nouns had different forms based on their case (nominative, accusative, genitive, dative) and number (singular or plural), causing changes in their endings.
Strong and Weak Verbs: Verbs in Old English were categorized as strong or weak depending on how they formed their past tense and past participles, resulting in irregular changes for strong verbs.
Vocabulary and Lexicon
The vocabulary of Old English is quite different from modern English, and many common words we use today have their roots in Old English.