Markers are little icons used in graphs on AppSignal.com to indicate a change. This can be a code deploy using a "Deploy marker" or a special event with a "Custom marker".
Custom markers can be used for anything from scaling operations, to sudden spikes in traffic and infrastructure issues such as when a database was acting up.
See also our announcement posts about Custom markers:
A custom marker can be created in two ways. Through the UI on AppSignal.com on the graphs or with a request to our API.
When on AppSignal.com open a page with a graph on it, any graph. Hover over a space in a graph and you will be presented with a "Add marker" button. In the "Add marker" lightbox, select an icon, set a message and create your marker. To edit or delete a marker, click on the icon and you will be brought back to the editor.
Please read our Markers API endpoint documentation page for more information on how to create a marker using the AppSignal API.