Digital signage advertising has become big business for several reasons. First, unlike old-style billboards, where an advertiser purchases the space for a particular period such as six months, digital signage can be easily programmed to change to different ads, thus allowing the space to be shared by several advertisers. Second, digital signage is not limited to a still image and, instead, can include moving video. For both reasons, frequent passersby may be more likely to pay attention and not ignore the sign in the same way they may if the ad remains unchanged for an extended period.
So if you think digital signs are more like television or website advertising then that is probably correct. Essentially, it is video advertising brought to public locations. Moreover, just as we see with television and desktop computers, the size of outdoor video screens is expanding. As discussed in this New York Times story, a new digital sign was just unveiled in Times Square. It is massive, measuring eight stories tall and spanning an entire city block (nearly 300 feet). Initially, this space will be occupied by a single advertiser, in this case Google. And how much will they pay to advertise? Well, this is not entirely clear though the story suggests it may cost $2.5 million for one month. At this price expect to see this space move from a space dedicated to single advertiser to one that is shared by multiple advertisers.