Next Level Cache improves performance by caching database queries.
Next Level Cache is a plugin that caches database queries to improve performance.
WordPress supports a special type of plugin known as a "Drop-in" which allows overriding of the class that controls access to the database. Next Level Cache intercepts queries and selectively caches them.
Updating any page or WordPress setting will clear the cache (changing the value isn't necessary, just click an update button somewhere).
A reset is when the entire cache is cleared after changes were made to a page or settings. Pruning is when the allotted space for the cache is filled and items are removed to decrease the size. Both of these are technically bad because the cache has to be re-generated for some or all of the pages. However a reset is a normal, unavoidable occurrence when pages or settings are updated. Excessive pruning, on the other hand, means that the cache is not functioning optimally and your site may even experience performance degradation. Next Level Cache keeps track of the number of prunes each day in order to detect and warn you of this situation. If the Next Level Cache dashboard widget or settings page is showing a warning about excessive pruning then Next Level Cache may not be the best caching plugin for your site.
The cache is stored in the wp_options table and is loaded upfront with one large query instead of many small ones.
I've minimally experimented with a few other caching plugins and Next Level Cache seems to be compatible with them. However, WordPress only allows one DB.php Drop-in file to be installed at a time. So if the other plugin requires it's own DB Drop-in then you would have to choose one over the other. Next Level Cache does not make any attempt to automatically copy or alter the DB.php. If there is a conflicting DB.php file installed then Next Level Cache will simply not do anything except to show a warning notification on the plugin settings page.
For the moment there are no configuration options, however there will be some options