Magento2 DevDocs available here

Configuration

Magento collects configuration from all modules, merges it, and saves the merged result to the cache. This cache also contains store-specific settings stored in the file system and database. Clean or flush this cache type after modifying configuration files.

Magento 2 devdocs

Source: Most xml config files located in etc/ directory; di.xml, config.xml, events.xml, extension_attributes.xml, product_types.xml, sections.xml, search_request.xml, sales.xml, payment.xml etc…

See \Magento\Framework\App\ObjectManager\ConfigLoader::load
\Magento\Framework\Config\Reader\Filesystem::__construct + config reader as \Magento\Framework\ObjectManager\Config\Reader\Dom::__construct, \Magento\Framework\Event\Config\Reader::__construct

Search pattern \$fileName = ‘(.*).xml’,\ to find them

Also see Configuration values loading order

Layouts

Compiled page layouts (that is, the layout components from all components). Clean or flush this cache type after modifying layout files.

Magento 2 devdocs

Source: xml files in layout/, page_layout/ directories and xml layout directives stored for each cms pages in admin (‘cms_page’ table in database)

See \Magento\Framework\View\Model\Layout\Merge::load

Blocks HTML output

HTML page fragments per block. Clean or flush this cache type after modifying the view layer.

Magento 2 devdocs

Source: *.phtml files

See \Magento\Framework\View\Element\AbstractBlock::toHtml

Collections Data

Results of database queries. If necessary, Magento cleans up this cache automatically, but third-party developers can put any data in any segment of the cache. Clean or flush this cache type if your custom module uses logic that results in cache entries that Magento cannot clean.

Magento 2 devdocs

Source: Collections queries

See \Magento\Framework\Data\Collection\Db\FetchStrategy\Cache::fetchAll

DDL

Database schema. If necessary, Magento cleans up this cache automatically, but third-party developers can put any data in any segment of the cache. Clean or flush this cache type after you make custom changes to the database schema. (In other words, updates that Magento does not make itself.) One way to update the database schema automatically is using the magento setup:db-schema:upgrade command.

Magento 2 devdocs

Source: db_schema.xml

Compiled config

Compilation configuration

Magento 2 devdocs

Source: Interceptors files generated in generated/ dir

Entity attribute value (EAV)

Metadata related to EAV attributes (for example, store labels, links to related PHP code, attribute rendering, search settings, and so on). You should not typically need to clean or flush this cache type.

Magento 2 devdocs

Source: eav tables

Page Cache

Generated HTML pages. If necessary, Magento cleans up this cache automatically, but third-party developers can put any data in any segment of the cache. Clean or flush this cache type after modifying code level that affects HTML output. It is recommended to keep this cache enabled because caching HTML improves performance significantly.

Magento 2 devdocs

Source: Whole rendered page (HTML)

See \Magento\PageCache\Model\App\FrontController\BuiltinPlugin::aroundDispatch

Reflection

Removes a dependency between the Webapi module and the Customer module.

Magento 2 devdocs

Source: Interfaces, not only for Customer module. Also used for Checkout, Quote, Tax and others

See \Magento\Framework\Reflection\MethodsMap::getMethodsMap

Integrations Configuration

Compiled integrations. Clean or flush this cache after changing or adding integrations.

Magento 2 devdocs

Source: integration.xml, integration/config.xml

Integrations API Configuration

Compiled integration APIs configuration of the Store’s Integrations.

Magento 2 devdocs

Source: integration/api.xml

Web Services Configuration

Caching the Web API Structure.

Magento 2 devdocs

Source: webapi.xml, webapi_async.xml

Translations

After merging translations from all modules, the merger cache will be cleaned.

Magento 2 devdocs

Source: xx_YY.csv from modules, themes, language packs and translations stored in ‘translation’ table for the current locale

See \Magento\Framework\Translate::loadData

Also see Translations loading order

Customer Notification

Temporary notifications that appear in the user interface.

Magento 2 devdocs

Source: \Magento\Customer\Model\Customer\NotificationStorage

See \Magento\Customer\Model\Plugin\CustomerNotification::beforeDispatch as example