I wish to download tiles in order to create an off line app with leaflet.
How can I do that?
Thanks
The preferred method is to install the rendering tool chain and render them on your own machine.
For very low volume use, a simple bit of reverse engineering, or just looking at the JOSM configuration will tell you what the tiles are called, and the rest of it is a leaflet/OS issue, not an OSM one.
Where do I find the rendering tool chain and documentation about the process?
Whilst I haven’t done this myself, https://switch2osm.org/serving-tiles/manually-building-a-tile-server-14-04/ describes one setup for rendering map tiles.