Angular Interceptors are a powerful feature in Angular's
HttpClient module, that allows us to process HTTP requests
before they are finally sent to a server. This concept of 'middleware' is also used in backend development to do similar things.
Let's keep this short and sweet. The Form Array  is a powerful feature within Angular which enables engineers to
manage form controls as elements in an array . Ultimately, think of it as an array, that's really all it is, however
it also gives us a lot of flexibility when building highly complex forms that require dynamic interaction such as creating
and deleting form controls (text inputs, radio buttons, etc). This feature was instrumental in my implementation of a
highly complex administration interface for an Investment Bank that required full configuration of the bank's data
hierarchy, including creating, editing and deletion of members of this hierarchy.
Observables are a key concept in Angular 4. The term is derived from the Observer Pattern which is used to observe state changes in objects that emit data (Observers). In other words, objects act accordingly based on something that they observe (the database changes, so the element says 'Database is updated'). This is an example use case of an observable being observed and why it is useful.
IPsec is a network security protocol used to provide security at the network layer of the OSI Model, where IP packets reside. IPsec processes data both inbound (traffic coming into the network) and outbound (traffic going outside of the network). It is quite comprehensive and as a result needs to be covered in quite a lot of detail, but overall it is just adding security to the network layer.
Angular 4? That's one of my initial questions when realising that Angular's latest upgrade from 2.0 was indeed Angular 4. There seems to have been a specific reason for this, which will not be explore in this tutorial. However we will look at Angular 4 in detail, starting with modules and then covering other aspects in upcoming posts.