Final answer:
Even without specific knowledge of Sonnet 18, it can be surmised that it is a Shakespearian sonnet likely delving into themes of love or beauty, written in iambic pentameter with a consistent rhyme scheme.
Step-by-step explanation:
Without knowing the specifics of Sonnet 18, we can infer that it is likely to address themes of love or beauty, common in sonnets, particularly given that it is a Shakespearian sonnet. This form traditionally comprises three quatrains and a final couplet, with a rhyme scheme of abab cdcd efef gg, and it adheres to iambic pentameter. The thematic content often revolves around romantic love, the nature of beauty, and sometimes reflections on life or mortality, wrapped within a tightly structured poetic form that allows for profound expression within rigid constraints.