# Terminologies used in Machine Learning

The various terminologies used in Machine Learning are -

#### Features

A set of variables that carry discriminating and characterizing information about the objects under consideration.

#### Feature Vector

A collection of r features ordered in a meaningful way into an n-dimensional column vector that represents the signature of the object to be identified.

#### Feature Space

Feature space is an n-dimensional space in which the feature vectors lie. An n-dimensional vector in an n-dimensional space constitutes a point in that space.

#### Class

The category to which a given object belongs to.

#### Decision Boundary

A boundary in the n-dimensional feature space that separates patterns of different classes from each other.

#### Classifier

An algorithm that adjusts its parameters to find the correct decision boundaries through a learning algorithm using a training dataset such that a cost function is minimized.

#### Error

Incorrect labeling of data by the machine learning algorithm.

#### Training Performance

The ability/performance of the machine learning algorithm to correctly identify the classes or target values of the training data, which it has already seen.

It is not a good indicator of generalization performance.

#### Generalization (Test Performance)

Generalization is the ability/performance of the machine learning algorithm to identify the classes or target values of previously unseen data.