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An algorithm is a step-by-step procedure for solving a specific problem or completing a task. It is used in computer programming to perform calculations, process data, and automate tasks. For example, a sorting algorithm such as QuickSort arranges a list of numbers in ascending order efficiently.

Use dynamic programming to build a table where each cell represents the length of the longest common subsequence up to those indices. For example, for 'abcde' and 'aceb', the longest common subsequence is 'ace' with length 3.

Use topological sorting to order nodes and then apply dynamic programming to find the longest path. For example, in a DAG with edges 1 -> 2, 1 -> 3, 2 -> 4, 3 -> 4, the longest path is 1 -> 2 -> 4 or 1 -> 3 -> 4.

A compiler is a program that translates source code written in a high-level programming language (such as C++ or Java) into machine code that a computer can execute. For example, the GNU C Compiler (GCC) compiles C code into executable machine instructions that the CPU can understand.

Use a hash map to count the frequency of each character, then iterate through the string to find the first character with a count of 1. For example, in 'swiss', the first non-repeating character is 'w'.

Binary search divides the search interval in half. Start with the middle element; if it matches the target, return it. Otherwise, adjust the search range to either the left or right half based on comparison. For example, searching for 4 in [1, 2, 3, 4, 5] returns index 3.

A firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predefined security rules. Its main purpose is to protect the network from unauthorized access. For example, a firewall can block suspicious traffic coming from the internet to protect your computer from malware.

A database is an organized collection of structured data stored electronically. Databases allow for efficient storage, retrieval, and management of data. For example, a customer relationship management (CRM) system stores information about customers, allowing businesses to track interactions and analyze customer behavior.

Use two pointers to traverse the linked lists. When one pointer reaches the end, move it to the start of the other list. Continue until both pointers meet. For example, if lists intersect at node with value 8, both pointers will eventually reach this node.

The `<header>` element typically contains introductory content or navigational aids, like headings or logo. Conversely, the `<footer>` element usually contains metadata about the section it is in, such as copyright information or contact details.

The `<nav>` element is used to define a block of navigation links. It helps to group together navigational links, making it easier for users and search engines to identify the main navigation areas of a webpage.

HTML5 is the fifth version of the HTML standard. It introduces new elements, attributes, and behaviors, enhancing the language's capability to create more dynamic and interactive web content. For example, `<article>` and `<section>` elements are used for better semantic structuring.

Semantic elements provide meaning to the web content, improving accessibility and SEO. Elements like `<header>`, `<footer>`, and `<article>` make the structure of web pages more understandable to both browsers and developers.

The `<section>` element represents a thematic grouping of content, typically with a heading. It's used to divide a webpage into logical sections. For instance, `<section>` can be used to group related content such as different articles or parts of a webpage.

The `<article>` element represents a self-contained piece of content that could be distributed independently. Examples include blog posts, news articles, or user comments. It should ideally contain a heading and content related to the heading.

The `<aside>` element is used for content that is tangentially related to the content around it, such as sidebars, pull quotes, or advertisements. It helps to separate supplementary content from the main content, improving page structure and accessibility.

`grid-template-areas` defines named grid areas within a grid container. It uses a string to assign names to specific grid cells. For example, `grid-template-areas: 'header header' 'sidebar content' 'footer footer';` creates a layout with named regions.

CSS Grid Layout areas are named regions in a grid. Defined with `grid-template-areas`, they simplify the placement of grid items. For example, `grid-template-areas: 'header header' 'main sidebar' 'footer footer';` organizes content into distinct sections.

`align-items` aligns flex items along the cross axis. Values include `flex-start`, `flex-end`, `center`, `baseline`, and `stretch`. For example, `align-items: center;` vertically centers items within the flex container.

`justify-content` aligns flex items along the main axis. Values include `flex-start`, `flex-end`, `center`, `space-between`, and `space-around`. For example, `justify-content: space-between;` distributes items with equal space between them and no space at the ends.

Use `position: sticky;` along with `top`, `right`, `bottom`, or `left` to create a sticky element that toggles between `relative` and `fixed` positioning based on scroll position. For example, `position: sticky; top: 0;` keeps the element at the top of its container as you scroll.

Node.js can interact with databases such as MongoDB, MySQL, or PostgreSQL using libraries like Mongoose or Sequelize. Example: Mongoose is an ORM for MongoDB, and Sequelize is used for SQL-based databases. The interaction is typically asynchronous using Promises or async/await.

readFile reads the entire file into memory, which can be inefficient for large files, whereas createReadStream reads the file in chunks, making it more memory efficient. Example: Use fs.createReadStream() when reading large files to prevent memory overload.

The 'require' function is used to import modules in Node.js, following the CommonJS module system. Example: To import the 'fs' module, you use 'const fs = require('fs');' to access file system operations like reading or writing files.

Express.js is a fast, minimal web framework for Node.js that simplifies server creation and request handling. Example: Express allows you to define routes and middleware in a structured way. A simple Express app might handle GET requests at '/home' with app.get('/home').