A patent is said to be infringed when a product/process violates the rights granted to a patentee.
To determine infringement of a patent by a product/process, one has to go through a section of a patent document called the claims. The claims section of a patent document describes in detail, the scope of protection granted to a patent.
The claims have to be analyzed in detail to find out if a product/process infringes upon the rights of a patentee. Depending on the nature of the claim, the claim would include a number of elements or process steps. Subsequently the scope of each of the elements/process steps has to be determined. Thereafter, your product/process has to be compared with the elements/process steps of the claim. The above comparison helps you determine whether the claimed elements/steps exist in your product/process.
A claim is said to be infringed if all the elements of the claim exists in your product. Similarly, a claim that includes process steps is said to be infringed, if all the process steps are present in the process that you intend to follow. In other words, if all the elements in the claims of the patent map on to the features of your product, your product is infringing upon the patent rights of the patentee.
It should be noted that, if your product does not have at least one essential element of the claim and does not fall under obvious replacements, then your product does not infringe upon the patent rights of the patentee.