This is the most commonly used distance measure. It is a special case of Minkowski's distance when the value of p = 2. In layman's term Euclidian distance can be defined as the shortest distance between the points.
Works well with low dimensional data
Good compatibility with KNN and HDBSCAN
Cannot be used for high dimensional data
Need to normalize before using
Not all the cases, shortest/ diagonal distance can be computed or doesn't meet the requirements. Thats where Manhattan distance comes in. It is also a special case of Minkowski's distance when the value of p = 1. Manhattan distance is defined as the distance between the real valued vectors ie the actual distance without considering the diagonal movements. It is also referred to as taxi cab or city block distance.
Works well with discrete/ binary attributes
Magnitude is high as the shortest distance is neglected
Less intutive for high dimension data
This is the next most commonly used distance measure after Euclidian. It is computed mainly to counter the high dimensional data problem faced by Euclidian distance. It is computed by measuring the cosine angle between the vectors.
Works well with high dimensional data where magnitude is not a major factor
Text Analysis
Magnitude is neglected
Considers only direction
Minkowski distance is used in normed vector space. There are three major requirements for this distance calculation.
Vector with length zero
Scalar Factor
Triangle Inequality