This is called "tagging for the renderer":

- https://wiki.openstreetmap.org/wiki/Tagging_for_the_renderer

This is accidentally drawing it so it "looks good" in OSM.org (the default "Carto" map colors), but it breaks other apps and styles!

For example, on Organic Maps, I see:

- 2 baseball icons completely overlapping right on top of each other.
- And the actual "baseball field" only shows the little infield "mushroom"-looking shapes.
- Night / Dark Mode only shows little "mushrooms".

So if you are marking stuff up correctly:

- 1 actual baseball field = 1 `leisure=pitch`!

- - -

If you wanted to go super "pretty", then there are Multipolygons:

- https://learnosm.org/en/beginner/id-editor/#drawing-multipolygons
- https://wiki.openstreetmap.org/wiki/Relation:multipolygon#iD

Multipolygons are used for the more complicated shapes, like when you:

- "Draw a building with a doughnut hole in the middle."

You could then mark the:

- "Outside" piece
-- leisure=pitch
-- sport=baseball
-- surface=grass
- "Inside" piece
-- natural=sand
-- surface=dirt

where the `surface`s are optional. (If you don't know if it's grass, turf, sand, or dirt, just leave it BLANK.)

- - -

To create a Multipolygon using OSM.org...

You can:

1. Press the "Area" button.
2. Draw the outer shape.
3. Draw the inner shape.
4. Shift+Left-Click on the outer shape and inner shape so both are highlighted.
5. Press 'C' (Merge) on your keyboard.
- (Or you can "Right-Click > Merge", it's the very first item if you select 2 objects.)

- - -

For example, you can see Multipolygons in:

- https://www.openstreetmap.org/way/92483447/history
--- Citizens Bank Park
--- Where the Phillies play.

Or even the "fancier" track & field I drew:

- https://www.openstreetmap.org/relation/17615316/history
--- Northwestern Lehigh High School

So instead of it just being a simple line around the track, it actually fills in the entire "oval" with the center cut out. :)

(That's actually how I learned about Multipolygons! I wondered how those track and field tracks looked so cool at many of the schools!)

- - -

So you can think:

- Areas are used whenever you have 1 solid shape.
- Lines are used when you have a super thin object.
- Multipolygons are used whenever you have more complex shapes (or "cutouts" in the middle!).

- - -

And note: Multipolygons get a bit trickier to edit... that's why I don't mess with them too much.