Final answer:
The data mining task of grouping individuals based on similarity without a specific purpose is known as cluster analysis, which can vary in methodology based on the data type and is used to discover patterns within data.
Step-by-step explanation:
The data mining task characterized by grouping individuals based on their similarity, without being influenced by any specific objective, is known as cluster analysis. This technique helps in building classifications of the sampled data. Cluster analysis can involve different approaches such as hierarchical or reticulate, divisive or agglomerative, and monothetic or polythetic classifications. The type of data being compared significantly affects the choice of method for cluster analysis. It can be used with both qualitative and quantitative data, and it helps to reveal natural patterns and distributions within the data, as would be illustrated by a population's distribution on a histogram.