Google Analytics shows 4 types of traffic (mediums) by default: Referrals, Organic, Paid, and Direct traffic.
In the documentation, Direct traffic is defined as URL’s that people either type in directly or reach via their browser bookmarks.
How does traffic categorization work for unpaid traffic? GA and other web analytics systems rely on an HTTP language header called “referrer” which passes the referring site user clicked on to reach the site.
However, the amount of Direct traffic often seems to be much higher than you’d expect. The reason for this is that GA actually categorizes all the traffic for which the source could not be recognized as “Direct.” The number of such instances is growing due to:
The best way to minimize false Direct traffic is to make sure to tag all your campaigns and controlled traffic, i.e. all email marketing and social media posts. This way, campaign traffic will be attributed to the right traffic source, regardless of where visitors clicked on it.
Having said that, it’s important to keep in mind that Direct traffic will always entail some level of mystery, as it includes all unrecognized traffic, in addition to true direct traffic.