Regular expressions, often abbreviated as "Regex," are sequences of characters that define a search pattern. They are primarily used in text processing to find, extract, or manipulate text patterns. Regular expressions provide a powerful and flexible way to search and manipulate text based on a specific pattern.

With regular expressions, you can, for example:

1. Search for text patterns: You can search for specific strings that match a defined pattern, such as email addresses, phone numbers, or URLs.

2. Extract text patterns: You can extract parts of a text that match a specific pattern, such as parsing data from a format.

3. Replace text patterns: You can replace text patterns in a text with other strings, such as substituting placeholders or removing unwanted characters.

Regular expressions are extremely flexible and allow the use of metacharacters and quantifying expressions to define complex patterns. They are supported in many programming languages and text editors and are a fundamental tool for text manipulation and analysis in software development, data processing, web development, and other fields.

SQL injection (SQLI) is a type of attack where an attacker injects malicious SQL code into input fields or parameters of a web page, which is then executed by the underlying database. This attack method exploits vulnerabilities in input validation to gain unauthorized access to or manipulate the database.

An example of SQL injection would be if an attacker enters an SQL command like "OR 1=1" into the username field of a login form. If the web application is not adequately protected against SQL injection, the attacker could successfully log in because the injected SQL command causes the query to always evaluate to true.

SQL injection can have various impacts, including:

1. Disclosure of confidential information from the database.
2. Manipulation of data in the database.
3. Execution of malicious actions on the server if the database supports privileged functions.
4. Destruction or corruption of data.

To protect against SQL injection attacks, web developers should employ secure programming practices, such as using parameterized queries or ORM (Object-Relational Mapping) frameworks to ensure all user inputs are handled securely. Additionally, it's important to conduct regular security audits and promptly install security patches.

Websockets are an advanced technology for bidirectional communication between a web browser (client) and a web server. Unlike traditional HTTP connections, which typically work in a unidirectional manner (from the client to the server), Websockets enable simultaneous communication in both directions.

Here are some key features of Websockets:

1. Bidirectional Communication: Websockets allow real-time communication between the client and server, with both parties able to send messages in both directions.

2. Low Latency: By establishing a persistent connection between the client and server, Websockets reduce latency compared to traditional HTTP requests, where a new connection has to be established for each request.

3. Efficiency: Websockets reduce overhead compared to HTTP, requiring fewer header details and relying on a single connection instead of establishing a new one for each request.

4. Support for Various Protocols: Websockets can use different protocols, including the WebSocket protocol itself, as well as Secure WebSocket (wss) for encrypted connections.

5. Event-Driven Communication: Websockets are well-suited for event-driven applications where real-time updates are required, such as in chat applications, real-time games, or live streaming.

Websockets are widely used in modern web applications to implement real-time functionalities. Using Websockets can make applications faster and more responsive, especially when dealing with dynamic or frequently changing data.

Function-as-a-Service (FaaS) is a cloud computing model that allows developers to execute individual functions or code snippets without having to worry about the underlying infrastructure. Essentially, FaaS enables developers to upload and run code in the form of functions without dealing with the deployment, scaling, or management of server infrastructure.

The idea behind FaaS is that developers only need to write and upload the code that fulfills a specific function. The FaaS platform then handles the execution of this code when triggered by events or requests. A typical example of FaaS is using serverless computing in the cloud, where developers deploy functions in the cloud that run only when needed.

Popular FaaS platforms include AWS Lambda by Amazon Web Services, Azure Functions by Microsoft Azure, and Google Cloud Functions by Google. They allow developers to upload and execute code in various programming languages, simplifying application development and scalability without worrying about the underlying infrastructure.

Garbage Collection is a process in many programming languages, including Java, that automatically manages memory in the computer that is no longer needed. When you write a program that allocates memory (for example, creating objects or variables), at some point, you may no longer need that memory.

Garbage Collection automatically identifies and removes such unused memory to free up resources and ensure efficient memory usage. It works by scanning the memory for objects that are no longer referenced or needed. These objects are then marked as "garbage," and the memory is reclaimed for reuse.

In Java, the JVM handles Garbage Collection. It tracks references to objects and identifies when an object is no longer reachable, allowing the memory occupied by that object to be freed. This simplifies programming as developers don't have to manually manage the deallocation of memory that is no longer needed.

The Java Virtual Machine (JVM) is a crucial component of the Java platform. It's a virtual machine that executes Java bytecode. When you write code in Java, you create human-readable code, which is then translated into Java bytecode by the compiler. This bytecode is platform-independent, meaning it can run on any machine that has a JVM, regardless of its operating system.

The JVM is responsible for translating Java bytecode into machine code and executing it on the specific hardware it's running on. It provides an environment for various functionalities such as memory and resource management, garbage collection (cleaning up memory that is no longer needed), and security mechanisms.

The JVM is an essential component that enables Java programs to run on different systems and platforms without requiring the code to be rewritten for each platform.