Google Analytics gives you the digital analytics tools you need to analyze data from all touchpoints in one place, for a deeper understanding of the customer experience. You can then share the insights that matter with your whole organization.
The Acquisition reports provide a window on your users' Acquisition-Behavior-Conversion (ABC) cycle: how you acquire users, their behavior on your site after acquisition, and their conversion patterns. .... read more
PERFORMANCE OF ADVERTISING POSITIONS
Ad performance is most often measured by the number of impressions or the number of clicks. The ratio between them is called CTR.
Wiki definition "Click-through rate, hence the term CTR, is the term used in online advertising, a clickthrough rate, that is, the ratio between the total number of impressions of Internet advertising and the number of clicks expressed as a percentage."
Add parameters to URLs to identify the campaigns that refer traffic.
By adding campaign parameters to the destination URLs you use in your ad campaigns, you can collect information about the overall efficacy of those campaigns, and also understand where the campaigns are more effective. For example, your Summer Sale campaign might be generating lots of revenue, but if you're running the campaign in several different social apps, you want to know which of them is sending you the customers who generate the most revenue. Or if you're running different versions of the campaign via email, video ads, and in-app ads, you can compare the results to see where your marketing is most effective.
Campaign URL builder: https://ga-dev-tools.appspot.com/campaign-url-builder/
... is a communications protocol for secure communication over a computer network which is widely used on the Internet. HTTPS consists of communication over Hypertext Transfer Protocol (HTTP) within a connection encrypted by Transport Layer Security, or its predecessor, Secure Sockets Layer. The main motivation for HTTPS is authentication of the visited website and protection of the privacy and integrity of the exchanged data. (more on wiki)
Why You cann´t see the source of traffic?
The HTTPS uniform resource identifier (URI) scheme has identical syntax to the standard HTTP scheme, aside from its scheme token. However, HTTPS signals the browser to use an added encryption layer of SSL/TLS to protect the traffic. SSL/TLS is especially suited for HTTP, since it can provide some protection even if only one side of the communication is authenticated. This is the case with HTTP transactions over the Internet, where typically only the server is authenticated (by the client examining the server's certificate).
Because HTTPS piggybacks HTTP entirely on top of TLS, the entirety of the underlying HTTP protocol can be encrypted. This includes the request URL (which particular web page was requested), query parameters, headers, and cookies (which often contain identity information about the user). However, because host (website) addresses and port numbers are necessarily part of the underlying TCP/IP protocols, HTTPS cannot protect their disclosure. In practice this means that even on a correctly configured web server, eavesdroppers can infer the IP address and port number of the web server (sometimes even the domain name e.g. www.example.org, but not the rest of the URL) that one is communicating with, as well as the amount (data transferred) and duration (length of session) of the communication, though not the content of the communication.
more you can find here: https://en.wikipedia.org/wiki/HTTPS