I have a question about the usage of 'furthermore', 'moreover', 'in addition to', and 'also'.
Dictionaries give "in addition to" as the meaning to all of them.
But what are the slight differences between these words? Which one is more formal?
Furthermore is commonly used in formal writing to delve deeper into a topic. 'What's more' can be used informally.
Moreover is often used in slightly informal communication to give a reason in support of an argument, apart from the one you already gave. While it does mean "in addition to" as the dictionary says, its usage is more appropriate in substitution of the phrase "not only that". 'Also' is more informal but serves the same purpose. 'Besides' can also be used in a similar context in informal communication since it means 'apart from'.
'in addition to' is used to simply mean something more or extra. e.g. 'Every summer, he is told to mentor the interns in addition to his routine responsibilities.'
'as well', 'besides that' and 'on top of that' are its informal variants.