The use of shapes is the key element in design.
The basic shapes like circles, squares and triangles can be very effective in designing a logo. From basic shapes it then possible to derive abstract shapes that arise from the composition of different elements: rounded contours, sharp ends, etc..

The more interesting thing, however, concerns the sub-conscious meaning that you can associate with each shape. It 'very important to know that meaning when making a logo or when it is required the creation.

• The circle is an enduring, endless and associated with protection.
• The square denotes stability, honesty and trust.
• The triangle may suggest tension.
 
Knowing what a shape communicates is one of those creative skills that every good designer must have in his cultural background. You should also be able to associate the right shape with what a brand wants to communicate and then tying it to the intrinsic characteristics of the client or company that requires the development of the logo.
All these considerations and this study can be found in big brands logos. For example, try to identifie logos of companies that belong to the same industry or service category and notice how often the same geometric shapes are applicants in the logos of these brands.

Here is a gallery of beautiful logos characterized by the use of geometric shapes.
Do this experiment: identify how you feel looking at one logo rather than another, this is the first step in exploring your creative sub-conscious.

Are you looking for other logos inspiration?

Initial Logos Collection

Typographic Logos Collection