You might be surprised to learn that the only requirement for a paragraph is that it expresses only one idea, thought or topic. The topic of the paragraph is introduced in the topic sentence, which is often the first sentence in the paragraph. There's no set length for a paragraph: a paragraph can be one sentence, or it can by very many sentences (but beware, long paragraphs can be very difficult to write - and even more difficult to read). The length of a paragraph depends on what the author is trying to communicate, but the really important thing to remember is that a paragraph must contain only one main idea.
As a basic 'rule of thumb', a paragraph has three parts:
1. A topic sentence: this is a sentence that introduces the idea. If you're a paragraph novice, you may want to make the topic sentence the first sentence you write, but as you progress towards paragraph grand master you may wish to try moving the topic sentence to a different position within the paragraph (did we really say paragraph writing wasn't exciting?!)
2. Supporting details: give examples, evidence and facts to build on the main idea.
3. Closing sentence: by definition, the last sentence. Can be used to re-state the main idea, or to make the transition to the next paragraph
Here's an example of this formula being used to construct a paragraph:
1. Topic sentence:Learning how to use paragraphs is a vital if you want to be able to communicate really well through your writing.2. Supporting details including...Explanation of the topic:A jumbled, illogical set of statements is very hard to understand and will not hold your readers attention.Example:Imagine if the next sentence in this paragraph was 'the zebra is perfectly adapted to life on the plains of Africa'. You wouldn't be able to follow my argument and wouldn't waste time reading further!Explanation:If you change topic, introduce another idea or give irrelevant detail, you will confuse your readers and your argument will lack impact.3. Closing sentence:So, if you want to keep your readers hooked, make sure your paragraphs are focused on building one idea only.The whole paragraph would read like this...Learning how to use paragraphs is a vital if you want to be able to communicate really well through your writing. A jumbled, illogical set of statements is very hard to understand and will not hold your readers attention. Imagine if the next sentence in this paragraph was 'the zebra is perfectly adapted to life on the plains of Africa'. You wouldn't be able to follow my argument and wouldn't waste time reading further! If you change topic, introduce another idea or give irrelevant detail, you will confuse your readers and your argument will lack impact. So, if you want to keep your readers hooked, make sure your paragraphs are focused on building one idea only.