OpenStreetMap also takes some get used to. I once mistook an contour line (denotes equal elevation) for a trail, and wondered why the "trail" needs so much bushwhacking.

OpenStreetMap is a dataset that can be rendered any way you want. Where did you see that map and what were the settings?

I downloaded OpenStreetMap data from OpenAndroMaps, and was viewing it in c:geo geocaching app. I figured out the difference between contour lines and trails, the second time around.

So this was probably the fault of how the c:geo app chooses to render those lines.

Does OSM actually store the data for contour lines? As a contributor, I thought not, and topography is an add-on.

Trails are usually dotted lines and contour lines are always solid lines, was this not the case here?

The article has a picture of the dotted line. It doesn’t appear to be a contour map at all.

The article doesn’t mention OSM at all

Downvoted by people not used to reading topographic maps I guess ;) In all seriousness though, not sure why it's being downvoted. Perhaps we are just misunderstanding each other? That's how topographic maps work so I'm asking if that was not the case here. Surely even the online topographic maps come with a legend?

I’m used to OS maps in the U.K., and yes, contours are quite obvious, and map reading is a basic skill learnt about age 8.

However there’s no guarentee a give OSM render will show contours, footpaths, and different rights of way, in the same way as OS, or have a legend.

Very true. I find their coverage excellent.