Hashing is used to ensure data integrity by generating a fixed-size hash value for a given input data. This hash value can be compared to verify data integrity during transmission or storage.

802.11a operates in the 5 GHz band, providing faster data rates but shorter range. 802.11b operates in the 2.4 GHz band with slower speeds but better range. 802.11g combines elements of both for improved speed and range.

Regression testing involves re-running test cases to ensure that new changes haven't adversely affected existing functionalities. It verifies that the code behavior remains unchanged post-modifications. This is crucial in software development to catch bugs introduced inadvertently during updates and to maintain overall system reliability and stability. It also helps in ensuring that new features don't break existing functionalities.

The Adapter design pattern allows objects with incompatible interfaces to work together. It acts as a bridge between the client and the target class, enabling communication and interaction. This pattern is useful when integrating existing systems that have incompatible interfaces or when designing reusable libraries that need to work with multiple interfaces.

Graph databases are ideal for handling complex relationships as they excel in managing interconnected data. Nodes represent entities like users, and edges represent relationships between them. This structure is well-suited for social networks where users have varied connections. Document databases are better suited for semi-structured data and may not handle complex relationships as effectively as graph databases. Columnar databases are optimized for analytical queries, not for complex relationship handling. Key-value databases are efficient for simple data retrieval but lack the structure needed for complex relationships.

Bubble sort has a time complexity of O(n^2) in the worst-case scenario. This means that for every element in the array, it may need to compare it with every other element, leading to a quadratic growth in time complexity as the input size increases.

The .gitignore file is used to specify intentionally untracked files that Git should ignore. This can include build artifacts, temporary files, and other files that should not be included in version control.

Server-side rendering (SSR) offers advantages like improved performance and SEO, but it also comes with challenges such as setup complexity and resource requirements. Both React and Angular support SSR, and developers must weigh the pros and cons carefully based on project requirements and their team's expertise to decide whether to implement SSR in their applications.

Functional dependency and transitive dependency are fundamental concepts in database normalization. Functional dependency refers to a situation where the value of one attribute uniquely determines the value of another attribute in a database table. For example, in a table of employees, if the employee ID uniquely determines the employee's email address, we say there is a functional dependency between ID and email. Transitive dependency, on the other hand, occurs when a non-key attribute determines another non-key attribute. For instance, if in the same employee table, the department name is determined by the manager's name, which in turn is determined by the employee ID, then we have a transitive dependency. The goal of normalization is to minimize or eliminate such dependencies to ensure data integrity and reduce redundancy.

SQL injection attacks occur when malicious code is inserted into SQL statements, exploiting vulnerabilities to manipulate the database. To prevent SQL injection, input data should be sanitized to remove any malicious code. Using stored procedures and encrypting database connections also enhance security but may not directly prevent SQL injection attacks.