A digital footprint consists of the sum total of online media and identity presence for an individual or entity and includes digital inputs such as status updates, bookmarks, reviews, search results, and any other content created or consumed.
In social media, digital footprint refers to the size of your online presence as it relates to the number of people you interact with and the extent to which those interactions are dynamically redistributed across the Social Web.
Overview - The Power Of Data & Your Digital Footprint
"Search is going to wear out over time. Web users want guides. The efficiency of search, which can get sort of better, still lacks the human touch. The human touch will add a lot of value." 
Whether you realize it or not there is real value created from the collection of your inputs and the analysis of that data is becoming an industry unto itself recommending everything from the blogs you might find interesting to favorite vacation spots.
However this data is also being used within peer networks as a means of discovering new content. We go to search engines to find out more about topics we've already discovered. Social networks are providing people with a new source of discovering information and expertise from groups of trusted peers with whom they share common interests.
Some of the most influential individuals and brands online today are those that have become trusted curators of information. They are creating prolific digital footprints of both original and shared content to establish authority and thought leadership in their field which is then leveraged to build trust and influence online.
Overview - Building A Discoverable Presence On The Social Web
"Reputation capital is a corporate asset that can be managed, accumulated and traded in for trust, legitimisation of a position of power and social recognition, a premium price for goods and services offered, a stronger willingness among shareholders to hold on to shares in times of crisis, or a stronger readiness to invest in the company’s stock." 
Klewes and Wreschniok
Building a more discoverable brand requires the creation of a robust, dynamic flow of information through social activity streams. The trail of information and media content that you publish within this 24/7 real time, living stream of data becomes an extension of your Digital Identity which impacts the impression people form about your brand and has the potential to increase your reputation capital.
A Value Driven Digital Footprint Enhances Discoverability
Creating relevant content and contributing to social groups which share an affinity with your brand will raise overall visibility and increase the likelihood of your message spreading throughout the network via sharing, bookmarking, voting and other social actions.
Consistent Contribution Builds Reputation Capital
The process of contributing content, when driven by an intent to provide value, conveys to your online audience a genuine interest in their needs. The more this perception is reinforced by the substance of your Digital Footprint the more reputation capital you will build with your audience.
Digital Media Streams Contributes to Network Growth & Visibility
Using traditional media channels and outreach strategies limits exposure to a narrow audience. Interactive digital media streams expose your brand content to a prolific and diverse audience thereby creating more opportunity to expand your audience base.
A Broad Based Digital Footprint Provides Measurable Data
Many aspects of your digital footprint can now be integrated with the Social Web and provide insight into how much attention your brand is getting. Sharing, bookmarking, commenting and tagging tools can be embedded on blogs and websites that offer back end analytics to measure viewership and sharing metrics.