(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.
Metadata related to EAV attributes (for example, store labels, links to related PHP code, attribute rendering, search settings, and so on).
We can conclude that there is a big difference in cache tag and cache key: cache tags are used as handles for clearing certain caches. Now let’s say your module contains system configuration that, after you change its values, has to either refresh or invalidate cache. The customer object, for example, maps to the Now, when someone reads or writes to our config value through the backend interface Magento instantiates our newly created model. Luckily, Magento already provides a model that does this!
Meet Be aware though, Magento considers invalidated cache types as disabled - Instead of showing the wrong thing, it chooses to not use cache at all.
Clean or flush this cache type if your custom module uses logic that results in cache entries that Magento cannot clean. If necessary, Magento cleans up this cache automatically, but third-party developers can put any data in any segment of the cache.
Maybe you created a cached block and you want it to clear/refresh its cache after a specific setting gets altered.On the contrary, if you only have your own tag, your HTML might contain old information as it might depend on store information or a static CMS block.The If the block contains data about a specific product (such as related products), you would need to add the product ID or SKU to the list - you don't want each product to show the same related products!You want to write the results of slow queries into the cache so they are quick to load when you need them, avoiding the need to execute the same slow queries over and over again.When the underlying data changes, you want to recalculate the results in a process known as cache invalidation.Cache tags exist so that we can selectively clear cache instances.