Look to the lower side of your Overlays menu to find all options related

to Normals. Enable the option to display normals for faces and increase

their size. Your normals appear as small perpendicular lines pointing out

of each face (Figure 4.12).

Figure 4.12 - Normals in object

You must be in Edit Mode to view and manipulate Normals as you can

see from Figure 4.12, the normals for part of the object point in opposite

directions. If you want a smooth surface for any object, all normals must

point in the same direction.

Tip: At the overlays menu, you can also enable the Statistics option to

display information about your modeling project on your 3D Viewport's

top left. The Statistics option is in the top left.

You can force the recalculation of normals using the SHIFT+N keys to

make Blender point all of them to the outside of a model. Before you

press the keys, make sure you select all faces from the object with the A

key. After selecting all faces, press SHIFT+N. The option is also

available from the Mesh → Normals → Recalculate Outside menu.