Most of us grew up on farms, ranches and ranges shooting with iron sights. In fact, my son just got his first scope this year after 2 years of trying to prove that he could hit an 8" plate at 300 yards open sights with a 243.
Technological advancements have brought about a new type of sight - the holographic weapon sight. Often also referred to as "Reflex Sights".
These sights have a laser that projects the image of a reticle on a pane of glass. The reflected image indicates the bullets point of impact at whatever range the shooter zeroed the sight.
There are several advantages to this technology as target acquisition and aiming are quicker, they are visible in low/no light conditions and they can actually correct the aim point should the shooter not be directly behind the sight.
First, because the shooter does not have to line up the front and rear sights as one would with standard sights, acquiring the target and aiming are much faster. This also aids us older shooters as it gets more difficult to see both the front and rear sights with our aging eyes.
The sights are self-illuminated. Because a laser projects the reticle, it is visible even in the darkest of conditions. Most of these sights even have multiple brightness settings.
Lastly, all but the worst of the holographic sights have error correction or "parallax" features built in. If you aren't right behind the sight, the sight is designed to adjust for your improper alignment so that as long as you can see the reticle, it indicates the point-of-impact.
Most first-time reflex sight users will probably close one eye as they would with a scope - losing their peripheral vision on that side. As these sights are primarily designed for fast target acquisition of close targets, this is not the preferred method of sighting. Both eyes should be kept open and the shooter should focus on the target, not the sight. This technique is called bridging as your brain combines the picture of your target from your off-gun eye, with the picture of the reticle from your on-gun eye creating the illusion that the reticle is painted over the target. The shooter maintains full peripheral vision and better depth perception. Very important capabilities in a CQB situation or while dealing with fast-moving targets like wild pigs.