The 'opacity-{number}' class in Bootstrap is used to adjust the opacity of an element, where the number can be between 0 and 1. For example, 'opacity-0.5' sets the opacity to 50%.

The 'position' utility classes in Bootstrap are employed to control the positioning of elements. The class 'position-static' sets the position to static, while 'position-absolute' positions an element absolutely within its containing element. This flexibility is crucial for achieving desired layouts and designs in a Bootstrap-based project.

In Razor views, @Model is referencing the data provided by the corresponding Controller Action Method. It's a way to pass data from the controller to the view for rendering. @Model.Name would typically access the 'Name' property of the model passed from the controller.

To ensure strong passwords, you should adjust the Password Complexity configuration in ASP.NET Core Identity. This configuration allows you to specify requirements like uppercase letters, digits, special characters, etc., making passwords more secure.

One of the key features of ASP.NET Core is its ability to run on Linux platforms, in addition to Windows and macOS. This cross-platform compatibility makes it a versatile choice for web application development, allowing deployment on a wide range of server environments.

The correct attribute typically used to identify a custom Tag Helper in Razor Views is [TagHelper]. This attribute marks a class as a Tag Helper, allowing it to be recognized and used in Razor Views. It's a crucial part of creating custom HTML elements or attributes that the Razor View Engine can process on the server-side.

For command-line operations in ASP.NET Core development, the dotnet CLI (Command Line Interface) is an indispensable tool. It allows developers to perform tasks like project creation, building, testing, and publishing without relying on an IDE. The CLI is essential for cross-platform development and automation.

Implementing the "Password Complexity" option in ASP.NET Core Identity helps enforce strong password policies, preventing users from setting easily guessable passwords. It typically includes requirements for length, character types, and complexity to enhance security.

The project.json file was replaced by the .csproj file in .NET Core 2.0 and later versions. .csproj files use XML to define project structure and dependencies, replacing the simpler JSON-based project.json format.

In attribute routing, when specifying the 'Order' property, a lower value indicates a higher priority. So, the route with 'Order = 2' will prioritize this route above other routes with no order specified. This allows you to control the order in which routes are matched and executed.