About 80 percent of the photos on Flickr are public and searchable by everyone. In one sense, it's a place where people upload snapshots from the family reunion, wedding or the birth of a baby or something like that, but it's also a place where people go to show what the world looks like to them.

If you work at a 10,000-person company, and you're using e-mail as the primary means of communication, then you probably have access to a couple hundredths of 1 percent of all the communications happening across the company. But if you use Slack, you might have access to 10 or 20 percent.

If you work at a 10,000-person company, and you're using e-mail as the primary means of communication, then you probably have access to a couple hundredths of 1 percent of all the communications happening across the company. But if you use Slack, you might have access to 10 or 20 percent.

There are a lot of things that Slack gives you that email doesn't when you think about internal use. Switching to Slack from email for internal communication gives you a lot more transparency.