Geometry (meshes)
Meshes are points joined into faces and edges: solid surfaces you can shade, texture, boolean and sculpt.
What a mesh is
A mesh is a point cloud with one extra ingredient, connectivity. The points become corners, the corners join into edges and faces, and the result is a continuous surface rather than loose dots.
That surface is what lets a sphere catch light and hold a texture. Nodes like Sphere and Cube hand you geometry directly, and any 3D import arrives as a mesh.
Like every collection, a mesh carries a table of attributes you can read and write. On top of @P it adds two that make surfaces look right:
@N, the surface normal, the direction a face is pointing. This drives shading and lighting.@uv, texture coordinates, the flat map telling an image how to wrap onto the surface.
Both ride per-corner, so a single face can blend smoothly across its vertices.
Points vs geometry
Use points when only positions matter: scattering, instancing, particles, drawing dots or lines. Use geometry when you need a real surface, something to light, texture, carve or thicken.
If a node talks about faces, edges, normals or volume, it needs geometry. All of these require a true mesh:
Boolean, combining shapes with union, subtract and intersect.
Bevel, rounding or chamfering corners and edges.
Subdivide, smoothing a blocky mesh into a flowing one.
Offset, shelling or thickening a surface along its normals.
Feed any of those a bare point cloud and there are no faces to work on.
Converting between points and meshes
Conversion happens automatically where one exists, and you can also do it on purpose.
Points → mesh. Build a surface from positions. Convex Hull wraps a tight skin around a point set, Mesh in its Extract Mesh mode grows a surface out of a field or a metaball blend of the points, and Connect Points stitches points into edges.
Mesh → points. Drop the faces and keep the corners as a point cloud, which is what scattering or instancing off a surface needs. This direction is lossy.
Convex Hull has a second job. Switch Mode to Decompose and instead of one hull it returns the convex parts that cover the shape, so an L stays an L as two boxes rather than a single hull that swallows the notch. Concavity decides how deep a dent a part may keep before it is split again, and Max Parts is a stop for pathological input rather than the usual control.
Mesh also remeshes geometry you already have, rebuilding its surface on an even grid. Voxel gives a smooth, uniform result, Blocks a faceted one, and Sharp keeps hard feature edges intact. Set Voxel Size in world units for a density that does not change when the object does. Turn Preserve Attributes on to carry @Cd across onto the new surface, which pulls the mesh back to the CPU; leave it off and the result stays on the GPU.
Turning a mesh into points throws away the connectivity: the faces, the edges, and the per-corner @uv and @N. Going back the other way rebuilds a surface from scratch and does not return the mesh you started with. Keep an un-converted copy upstream if you might need the surface again.
For a flat shape lifted into 3D rather than a full mesh, many 2D analytic shapes can be extruded or swept with Sweep, which is lighter than modelling a solid by hand.