The Acquisition section in Google Analytics tells you where your visitors originated from, such as search engines, social networks or website referrals. This is a key section when determining which online marketing tactics are bringing the most visitors to your website.
Source: the origin of your traffic, such as a search engine (for example, google) or a domain (example.com).
Medium: the general category of the source, for example, organic search (organic), cost-per-click paid search (cpc), web referral (referral).
Source/Medium is a dimension that combines the dimensions Source and Medium. Examples of Source/Medium include google/organic, example.com/referral, and newsletter9-2014/email.
Channel Groupings are rule-based groupings of your traffic sources. Throughout Analytics reports, the data is organized according to the Default Channel Grouping, a grouping of the most common sources of traffic, like Paid Search and Direct. This allows you to quickly check the performance of each of your traffic channels.
The default channels are:
Direct (direct traffic has no medium specified)
Organic Search (medium will exactly match “organic”)
Social (medium matches “social”, “social network”, “social media”, “sm”, “social media”, or “social network”)
Email (medium will exactly match “email”)
Affiliates (medium will exactly match “affiliate”)
Referral (medium will exactly match “referral”)
Paid Search (medium will exactly match “cpc”, “ppc”, or “paidsearch” but won’t exactly match “Content” in Google’s Ad Distribution Network – basically another variable Google brings in from paid campaigns)
Other Advertising (medium will exactly match “cpv”, “cpa”, “cpp”, or “content-text”)
Display (medium will exactly match “display”, “cpm”, or “banner” or Google’s Ad Distribution Network exactly matches “Content”)
(other) (the session doesn’t match any of the above)