In the context of data visualization in Python, Seaborn is a library based on Matplotlib that simplifies the creation of statistical graphics, making them more attractive and informative.

In Seaborn, the sns.scatterplot() function is used to create scatter plots with the possibility of several semantic groupings. It allows you to color and style the points based on additional variables, making it useful for exploring relationships in complex datasets.

In Seaborn, you use the distplot function to plot univariate distributions of observations. It's a versatile function that can display histograms, kernel density estimates, and more.

To visualize the linear relationship between two variables in Seaborn, you can use a regression plot. It shows a scatter plot of the data points with a regression line, helping you assess the strength and direction of the linear relationship.

In Scikit-learn, the score method is used to calculate various metrics, including accuracy, to evaluate the performance of a machine learning model on test data. This method compares the model's predictions to the true labels and returns the accuracy score.

In Scikit-learn, the StandardScaler class is used for feature scaling. Feature scaling is crucial in machine learning to ensure that all features have the same scale, preventing some features from dominating others during model training. StandardScaler standardizes features by removing the mean and scaling to unit variance.

In Scikit-learn, the LabelEncoder class is used to encode categorical variables into numerical format. It assigns a unique integer to each category, which can be useful when working with machine learning algorithms that require numerical input. This transformation is essential to handle categorical data effectively in many machine learning tasks.

In Scikit-learn, the fit method is used to train a machine learning model using the training data. This method takes the training data as input and adjusts the model's parameters to make predictions on new data.

In RESTful API development, the acronym CRUD stands for Create, Retrieve, Update, Delete. These are the four basic operations that can be performed on resources in a RESTful API.

In Python's unittest framework, the assertEqual() method is used to compare whether two values are equal. It is an essential method for writing test cases to ensure expected and actual values match.

To define a metaclass within a class definition in Python, you use the keyword metaclass. This keyword specifies the metaclass for the class, allowing you to customize how the class is created and behaves.

In Python, the 'break' statement is used to interrupt loop iteration and exit the loop prematurely. When 'break' is encountered inside a loop, it jumps to the next statement after the loop.