Key Takeaways

  • Patent classification organizes inventions into technical categories, making searches for existing patents faster and more accurate.
  • The International Patent Classification (IPC) system, created under the Strasbourg Agreement, is the global standard.
  • The U.S. Patent Classification (USPC) and Cooperative Patent Classification (CPC) systems refine categorization for regional and international patent offices.
  • Patent classification helps prevent duplication, improves prior art searches, and supports innovation analysis across industries.
  • Inventors can use classification codes to identify similar patents and ensure their inventions meet novelty requirements.

Classification of Patents

Classification of patents is used to make it easier for individuals to perform a search of existing patents. 

Inventions are sorted into different fields of technology with a system using unique codes in a classification scheme. Each invention is put into a class with others that all fit into a particular technical area. Patents that are processed and granted, as well as those in progress, are all classified into their technology areas. 

When a company or inventor wants to begin a new project, he or she needs to perform a patent search to be sure the invention is original. Accurate results are essential, so this is where the classification system comes in. Patent documents use particular lingo that would not work well with a simple keyword search. 

Whichever authority is involved in processing and approving patents will determine the type of classification code used for the invention.

The various systems used for classification of patents are: 

Why Patent Classification Matters

Patent classification is more than just a filing formality—it’s a critical part of the patent examination and innovation tracking process. Classifying patents accurately ensures that:

  • Patent examiners can efficiently find relevant prior art during examination.
  • Inventors and companies can identify similar inventions, reducing the risk of duplication or infringement.
  • Researchers and analysts can monitor technology trends, innovation activity, and market developments.

By organizing patent data into hierarchical categories, authorities and businesses can better analyze innovation at both micro and macro levels—across industries, technologies, and regions.

Characteristics of Patents

Patents are made up of different elements; all meant to clarify the vision, purpose, and plans for the invention, among other things. 

Patents include the following:

  • Descriptions (including drawings)
  • Claims
  • Abstracts
  • Dates
  • Classification
  • Ownership (inventor or applicant)

The prior art (or what was done or used before the invention was implemented) begins the description. This section is meant to make it clear how the invention is original, how it differs from what we use currently, and how it will spur on future development. 

You'll want to do the following in a description:

  • Give the invention a name
  • Provide a history of the patent 
  • Put the invention into a technical field 
  • Summarize how the invention works
  • Provide detailed drawings and explanations of them
  • Provide a thorough description of how the invention works and what it does 

A claim makes clear what the inventor is claiming as his or her intellectual property, basically, what the inventor wants to protect. How much the patent protects and its legal boundaries are laid out in the claim. The abstract provides a brief summary of what is found in the patent document.

Patents include a classification number or symbol to make them easy to find. Of the three previously mentioned codes, the IPC system is the most commonly used. 

The date included in the patent states when the product was invented and its period of protection. Here you'll see a list of dates including:

  • The application date
  • The first time the application was filed or the "priority date"
  • The date the patent was granted

Names and addresses of the inventor, applicant, or owner of the patent will all be found in the document. 

Role of Classification in Patent Search and Examination

Patent classification systems play a vital role in prior art searches and the patent examination process. During review, examiners rely heavily on these codes to locate comparable inventions efficiently. Without them, searches would depend solely on keyword matches—which are often unreliable due to the technical and specialized nature of patent language.

Patent search databases, including those maintained by the United States Patent and Trademark Office (USPTO) and World Intellectual Property Organization (WIPO), are indexed by classification codes. This structure allows inventors, legal professionals, and researchers to narrow searches by technology category rather than just words.

For example, if an inventor develops a new type of lithium-ion battery, using the correct classification code for energy storage devices allows for a targeted search of relevant prior art. This process strengthens both the accuracy of search results and the quality of granted patents.

International Patent Classification

The International Patent Classification, or IPC, is the most important system used for the classification of patents today. This system began in 1971 with the Strasbourg Agreement, which called for a new way of keeping track of and organizing patents. 

Patents are classified into different groups, depending on the type of technology they pertain to, using symbols and an organized hierarchy. You'll find almost 70,000 codes within all the various technical areas. This system is updated every year on New Year's Day. 

You'll find the following sections of technology are used for classification:

  • Human needs
  • Operations (including transportation)
  • Chemistry (including metallurgy)
  • Textiles (including fabric and paper)
  • Fixed constructions
  • Mechanical engineering (including forms of lighting, heating, weaponry, and engines)
  • Physics
  • Electricity

The International Patent Classification uses a hierarchical system to narrow down patents into subsets to be most distinctive. First, the patent is put into one of the sections listed previously, then a class, subclass, group, and finally a subgroup.  

Structure and Organization of IPC Codes

Each International Patent Classification (IPC) code is made up of alphanumeric symbols that represent a hierarchy of technological detail. The structure typically follows this format:

  • Section (A–H) – Broad categories such as “Human Necessities” or “Electricity.”
  • Class – A narrower field within the section.
  • Subclass – A subdivision of the class, focusing on a more specific technology.
  • Main Group – Covers general inventions in that subclass.
  • Subgroup – Covers detailed or specialized aspects of the invention.

For example, the IPC code H04W 12/06 refers to “Wireless communication networks; Security arrangements; Authentication.” Such detailed classification allows patents to be pinpointed precisely within vast databases of international patent documents.

U.S. Patent Classification

The USPC classification of patents organizes all patents and other similar documentation filed in the United States. This system groups documents based on the subjects they cover into 450 different classes and 150,000 unique subclasses. 

Transition from USPC to CPC

While the U.S. Patent Classification (USPC) system served as the primary framework for decades, it was officially replaced by the Cooperative Patent Classification (CPC) system in 2015. The move aimed to harmonize the U.S. patent database with international systems, particularly those used in Europe.

The CPC expands upon the USPC by offering more granular categories—approximately 250,000 classification entries compared to USPC’s 150,000. This enhanced detail improves search precision and ensures better alignment between the USPTO and the European Patent Office (EPO), making it easier to perform global patent searches and comparative analyses.

Cooperative Patent Classification

An extension of the IPC, the Cooperative Patent Classification system organizes patents into even more specific categories. This classification is a cooperation between the patent and the trademark offices of the United States and Europe. The harmonization of these systems is meant to allow for easier searches between the two different offices.

Benefits of the Cooperative Patent Classification System

The Cooperative Patent Classification (CPC) offers several advantages for inventors, patent examiners, and researchers:

  • Enhanced search precision: With its detailed structure, CPC enables highly specific categorization and retrieval of patents.
  • Global consistency: Since CPC harmonizes U.S. and European classifications, it promotes consistency across international patent systems.
  • Improved data analytics: The system allows for comprehensive trend analysis across countries and industries.
  • Faster examination: Shared databases between USPTO and EPO streamline cross-referencing and prior art identification.

The CPC also supports emerging technologies—such as artificial intelligence, renewable energy, and biotechnology—by regularly updating classifications to reflect new fields of innovation.

How to Use Patent Classification Codes in Searches

Inventors and businesses can use patent classification codes to conduct more efficient searches on databases like USPTO’s PatFT, Google Patents, and WIPO’s PATENTSCOPE. To do this:

  1. Identify the relevant code: Review similar patents or use keyword tools in these databases to locate applicable IPC or CPC codes.
  2. Search by classification: Use the code directly in the database’s “classification” field for a more targeted search.
  3. Combine with keywords: Merge classification codes with keywords to refine results.
  4. Analyze competitors: Review the classifications used in competitor patents to identify technological focus areas.

This method saves time and ensures that searches include all relevant patents—even those that don’t use your chosen keywords.

Frequently Asked Questions

1. What is the main purpose of patent classification?

Patent classification organizes inventions into technical categories to make it easier to search for, analyze, and compare patents.

2. How many main sections exist in the International Patent Classification system?

There are eight main sections, ranging from “Human Necessities” to “Electricity.”

3. What replaced the U.S. Patent Classification system?

The Cooperative Patent Classification (CPC) system replaced the USPC in 2015, aligning U.S. and European patent databases.

4. Can inventors use classification codes in patent searches?

Yes. Using classification codes allows inventors to perform more precise and comprehensive prior art searches.

5. How often are patent classification systems updated?

The IPC and CPC systems are updated annually to reflect emerging technologies and new areas of innovation.

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