Sectional views are drawn to show the internal details of an object.
The object is assumed to be cut on a plane.
The surface produced by cutting an object at this plane is called a section.
The surface which cuts the object at the section plane is shown hatched (a regular pattern) according to standard conventions.
Sections are of many types:
1. Full section
2. Offset section
3. Half section
4. Revolved section
5. Removed section
6. Partial section, or broken section
7. Auxillary section 
The type of section to be adopted depends upon the shape of the object.

Partial section:
A section consisting of less than half a section is called a partial section. 
Note that here we use a broken line to indicate the division between the sectioned and unsectioned part.
For this reason, a partial section is often called a Broken-out section.Half section:
This is generally used for symmetrical objects.
Two cutting planes at right angles to each other pass halfway through the view up to the centerline.
Thus only one quarter is assumed to be removed.Revolved section:
It is used to show the cross-section shape of ribs, arms, spoke, etc.

The section line is drawn by passing a cutting plane at right angles to the axis.
This section is then revolved and drawn at the cutting plane axis on the main view. 
If the crosssection changes along the length, many revolved sections can be drawn.  
When the sectional view is shown within the object it is known as a Revolved section.

Removed section:
It is similar to Revolved section, but instead of drawing the section on the view, it is drawn in a free space near the object along the centerline of the section.

Full section:
The cutting plane passes entirely through the object in a straight line. 
Thin objects like ribs, etc. are not hatched even if they are cut by the cutting plane along the axis.
To see the internal features of an object that are not in a straight line, the cutting plane can be offset. 
Such a section is called the Offset section. 
The cutting plane can be inclined also.