Answer: Phrases are commonly used as introductions to a sentence. Words like 'however,' 'indeed,' 'therefore;' phrases like 'on the one hand,' 'in particular,' 'for example,' and 'in the meantime' are examples of introductory language that ought to be concluded with a comma when they begin a sentence.
Example: However, On the other hand, Furthermore, Therefore, Thereafter, Consequently, Next, Finally, In conclusion, For example, Ultimately, etc.