The tiny English word so has numerous uses. Merriam-Webster gives it separate entries as adverb, conjunction, adjective and pronoun.
Most of the time, little so goes about its business unnoticed, but one of its functions has been provoking heated discussion on the Web: the use of so as “a discourse marker.”
The term “discourse marker” was coined in the 1960s to describe “a word or phrase whose function is to organize discourse into segments and situate a clause, sentence, etc., within a larger context.”
Here are some words and phrases commonly used as discourse markers in speech:
These are words we all interject into speech for reasons that have nothing to do with grammar. For example:
Well, I was a little worried.
Now, a clever man would put the poison into his own goblet.
You know, not everyone shares your opinion on that.
OK, let’s take a vote.
I think I’ll go now.
These markers serve no grammatical function, but they do advance discourse in various ways.