conversation so how was your day
Flickr/Arlo Bates
So everyone is starting their sentences with the word "so" these days. 
Fast Company recently attacked the use of "so" at the start of sentences, claiming it insults your audience, undermines your credibility, and demonstrates discomfort with the subject matter.
But linguistically, the use of "so" at the beginning of sentences can serve an important function.
Facebook CEO Mark Zuckerberg notoriously uses "so" to start sentences. In a Q&A with New York Times' blog Bits last month, he dropped it four times in just the first answer.
"So Facebook is not one thing," he said.
"So what we want to do is build a pipeline of experiences for people to have."
The word "so" appears at the beginning of sentences in two ways: before questions and before answers, especially during interviews, Galina Bolden, associate professor of communication at Rutgers University, who published research in 2008, focusing on the first example. According to data from both the U.S. and U.K. in the 1970s through the 2000s, however, the former is much more common.
"So" at the start of a question often marks the beginning of a new topic that one of the parties wants to discuss, often called an "interactional agenda," according to Bolden.
"When I ask — 'So how did your interview go?' — I indicate that I've been meaning to ask this question for a while, that it's been on my mind, or incipient," she explained. 
But Fast Company's Hunter Thurman wrote that a speaker's use of "so" indicates something rehearsed and dumbed-down. As a result, he claims, "so" alienates your audience.
But the transformation of "so" from a midsentence conjunction to an interjection at the beginning of questions contributes to human relationships, according to Bolden.
"It communicates that the speaker is interested in or concerned about the recipient," Bolden said. "It also invokes prior conversations between the speaker and the recipient, drawing on their relationship history." 
While Bolden said "so" appears less frequently before answers, the journalist Michael Lewis noticed its prevalence when exploring Silicon Valley for his 2001 book "The New Thing," The New York Times reported. He claims programmers, especially of the Microsoft variety, started, or at least popularized, beginning answers with "so." Maybe that's where Zuck learned it.
"'So' cuts across the borders within the computing class just as 'like' cuts across the borders within the class of adolescent girls," he wrote. Many Silicon Valley engineers learn English as their second language — and almost all of them speak this way, according to Lewis. 
But Bolden, although not a historical linguist, has her doubts about Lewis' claims. She hasn't seen any convincing evidence for "so" starting in Silicon Valley. It appears in writing as far back as Chaucer and Shakespeare. 
The "so" boom is likely a natural progression of language — not a spinoff of tech-industry jargon. And it's helping us communicate better.