How data collection works is GA (Google Analytics)

How data collection works:
- "Beacon" -ALL of these code pieces send data to
    google analytics as a simple "beacon"
- each pageview, event, etc. sends data to Google Analytics and it looks like this
- Same with GA Fired by google tag manager

Tools-
1. Firebug lite for google chrome
2. Google analytics debugger
3. Tag assistant (by google)

Measurement Protocol:
- Sent beacon to GA
- You can send customized values to GA and they will track if for you

Read here more about Measurement Protocol

How GA data is collected
1. Most website send data to Google with Each page load using JavaScript
2. Or they choose to send data using GTM
3. But we can also send data for each mobile app screen viewed
4. We can track everything else using the Measurement protocol

Implementation rules for your site
1. see if there is an easy way to implement with Java Script
2. Use pre-defined libraries whenever possible (Like SDK and Java Script)
3. More advanced businesses may use measurement protocol
4. None of these additional tools are required and they can be hard

Measurement Protocol Misuse:
Measurement protocol is misused by spammers to send spam data to your analytics account