The Shading tab can be used to enter Shader Editor. The preview is displayed at the top of the screen, while the Shader Editor is displayed at the bottom. You may also access the Shader Editor by clicking the icon in the upper left corner of the screen.
Find the shading modes in the top right corner of your 3D viewport to alter the viewport shading mode. Use solid shading for modelling, material preview for materials, texturing, and shading as a rule of thumb. The rendered view, on the other hand, is used for lighting setup and rendering.
The simplest method is to choose a mesh object and select Shade Smooth in the Object menu in Object Mode to make an entire object smooth or faceted. When you add or delete geometry, the "smoothing" attribute is automatically assigned to each face in the mesh.
The slots are used to provide different faces in the same item different materials. If you just have one slot, you can give your object substance by pressing the button you marked. You can select faces in Edit Mode and assign them to specific slots.
A Shader is a user-defined software that runs on a graphics processor's stage. Shaders are programmable stages in the rendering pipeline that offer code. They can also be utilised for general on-GPU computation in a little more constrained manner.
