Meteor™ Learning Note

Dependency Tracking in Meteor: Computations
While Meteor is a real-time, reactive framework, not all of the code inside a Meteor app is reactive. If this were the case, your whole app would re-run every time anything changed. Instead, reactivity is limited to specific areas of your code, and we call these areas computations.
Any files here are only served to the client. This is a good place to keep your HTML, CSS, and UI-related JavaScript code.

When Should We Use observe()?
Using the above pattern is sometimes necessary, especially when dealing with third-party widgets. For example, let’s imagine we want to add or remove pins on a map in real time based on Collection data (say, to show the locations of currently logged in users).
In such cases, you’ll need to use observe() callbacks in order to get the map to “talk” with the Meteor collection and know how to react to data changes. For example, you would rely on the added and removed callbacks to call the map API’s own dropPin() or removePin() methods.

Any files in this directory are only used on the server, and are never sent to the client. Use /server to store source files with sensitive logic or data that should not be visible to the client.

Files in /public are served to the client as-is. Use this to store assets such as images. For example, if you have an image located at /public/background.png, you can include it in your HTML with or in your CSS with background-image:
url(/background.png). Note that /public is not part of the image URL.

These files can only be accessed by server code through Assets API and are not accessible to the client.