The paragraph is the usual unit of a text. A paragraph is a logical grouping of several sentences about a topic or idea. The sentences in the paragraph should relate to one another as the idea moves logically from one sentence to the next and is developed.
Topic sentence and progression
Each paragraph should start with a topic sentence, which sets the reader up to understand what the paragraph will cover. Once stated in the first sentence, the topic is developed in successive sentences of the paragraph:
A cold can present with many symptoms. [topic sentence] Sneezing is a common and relatively mild symptom. Congestion can be a more serious symptom, which can lead to disturbed sleep and even sinus, bronchial or chest infections. [topic progression]
When there is a mix of items to be communicated in a paragraph, they need to be presented in a logical order (e.g. chronological, or their importance for the intended reader). There is no single ‘right’ way; it simply needs to be logical:
The day will start with a morning panel discussion, then move to break-out sessions with specialists, followed by Q&A and a buffet lunch. Next, we will have our keynote speech. After afternoon tea, the workshop will close with a ‘wrap-up’ session.
[This version delivers information about the components of the workshop chronologically.]
The day will include a morning panel discussion, break-out sessions with specialists, Q&A, the keynote speech, and a closing ‘wrap-up’ session. We will also have a buffet lunch and an afternoon tea break.
[This version begins by highlighting the business components of the day, and then tells readers about the catering arrangements.]
Paragraph size
Paragraphs are most effective when they are kept to a length of around 5 sentences. But shorter and even single-sentence paragraphs can draw attention to key points that might otherwise be buried. This can be useful in writing web content or material that needs to engage the reader in a short space, such as a media release or brochure.