Marketing automation is software which allows marketing individuals to scale their campaigning efforts through a variety of channels.  It automates the heavy lifting associated with broadcasting your message to a wide audience and driving inbound interest.  This is achieved through the crafting of email templates and their associated tracking, campaigns which automate the sending of those emails, and response logic to the leads targeted by those campaigns.  Most marketing automation packages perform some type of lead scoring designed to help sales and marketing prioritize pursuit of those leads.  Some marketing automation platforms address the entire funnel at less depth, while others go into greater depth for one part of the funnel and partner with other companies to fill in the rest.