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 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 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 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 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 Python, the yield keyword is used to define a generator function. A generator function produces a sequence of values using the yield statement and can be paused and resumed during execution, allowing for efficient iteration over large data sets.

In Python, the len() function is used to get the number of elements in various data structures, including sets. It returns the length or size of the set.

In Python, the __init__() method is a special method (constructor) used to initialize the object's attributes when an object is created from a class. It allows you to set up the initial state of the object.

In Python, the __add__ method is used to overload the + operator for custom objects. This allows you to define custom behavior when two objects of your class are added together using the + operator.

In Python, a module is a file containing Python definitions and statements. These modules are intended for use in other Python programs to organize code into reusable components.