Basics of Modeling
Element
3D objects consist of elements called vertices, edges, and faces.
When two vertices are connected, they form an edge, and when at least three edges converge, they form a face.
Faces with three points are called Triangle, with four points are called quad, and with more points are called N-gons or polygons.
When multiple faces are connected, they form a single object.
3D modeling involves adding or moving these vertices, edges, and faces to create shapes.
While 3D software interprets objects' faces as triangles for recognition, it's much more convenient for modeling to use quad shapes rather than triangles.
Thus, it's recommended to model in quad shapes whenever possible.
Also, be cautious with N-gons, as they can cause issues during subdivision, UV mapping, or rigging.
In UModeler X, you can modify these three elements and select each one using the icons provided.
When you select an element, it's highlighted in the Scene View, and options specific to that element appear in the inspector window.