Firstly is a more formal word, often used in writing, especially academic or professional writing. It's considered more appropriate in situations where you want to convey a sense of order and formality.
First is more versatile and can be used in both formal and informal contexts. It's a more conversational word and can be used in both writing and speech.
Here's a breakdown:
Use "Firstly" when:
* You want to emphasize the order of points in a list.
* You're writing formally, such as in a research paper or academic essay.
* You're using it to introduce the first point in a series of arguments.
Use "First" when:
* You're writing in a more informal style.
* You're speaking instead of writing.
* You're using it to describe the first item in a list or sequence.
Ultimately, the choice between "first" and "firstly" is a matter of style and preference. There's no hard and fast rule, and both words are grammatically correct.
Example:
* Formal: Firstly, I would like to thank everyone for attending.
* Informal: First, let's all have a toast to the birthday girl.
Both examples are correct, and the choice depends on the tone and context of the situation.