Alerts are a way for users to save searches they run frequently and receive notifications when new results are available that match a pre-defined query. The default LucidWorks Platform Search UI includes an example of how these might be implemented for users. An API is also available if you are designing a local search UI.
Alerts work by sending an email to users when new documents are added to the index that match their saved query. With LucidWorks Enterprise, the email server must be configured before alert notifications will be sent, which is done via the System Settings page. LucidWorks Cloud customers have a pre-configured mail server and do not need any further setup.