> For the complete documentation index, see [llms.txt](https://time-series-features.gitbook.io/catch22/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://time-series-features.gitbook.io/catch22/information-about-catch22/feature-descriptions.md). # Feature Descriptions This chapter contains an overview table of the catch22 features as well as detailed descriptions and examples of each feature, organized into 9 distinct conceptual categories. The *catch22* feature set provides open access to a powerful set of time-series analysis features that implemented efficiently for fast native feature computation in multiple coding languages. But the features (taken from the larger *hctsa* time-series feature set) can be hard to interpret :disappointed\_relieved: The material in this chapter should help you to understand what each of these 22 features is doing, and point you to the relevant time-series theory that underpins it. {% hint style="info" %} **catch22 v1.0**: These pages describe *catch22* v1.0, in which each feature exactly reproduces a piece of *hctsa* code (listed in the [feature overview table](https://time-series-features.gitbook.io/catch22/information-about-catch22/pages/Xul45GNpdBAJ3I0nN7Kt#feature-names-before-v1.0-and-hctsa-code)). Some features were renamed, the values of some features changed, and features that cannot be estimated (e.g., for a constant time series) are now [masked](/catch22/information-about-catch22/feature-descriptions/feature-overview-table.md#masking) by default. Where v1.0 changes a feature, its description includes a note on how earlier versions behaved, and the changes are summarised in the [feature overview table](https://time-series-features.gitbook.io/catch22/information-about-catch22/pages/Xul45GNpdBAJ3I0nN7Kt#changes-in-v1.0). {% endhint %} ## *catch22* Feature Descriptions Select the feature overview table for a high level description of each feature, or delve into detailed explanations and examples by exploring each of the 9 categories of time-series features included in *catch22*:


Feature overview table	Feature Overview Table	table_of_spis_light.png
Distribution shape	Distribution shape	dist_shape_light.png
Extreme event timing	Extreme event timing	extreme_event_light.png
Linear autocorrelation structure	Linear autocorrelation structure	linear_autocorr_light.png
Nonlinear autocorrelation	Nonlinear autocorrelation	non_linear_autocorr_icon.png
Symbolic	Symbolic	symbolic_light.png
Incremental differences	Incremental differences	incremental_diff_light.png
Simple forecasting	Simple forecasting	forecasting_light.png
Self-affine scaling	Self-affine scaling	self_affine_light.png
Other	Other	other_light.png

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