The U.S. trademarks database, formally known as the U.S. Patent and Trademark Database, stores patent data from 1790 to present day and trademark data from 1890 to present day. 

The database includes information about history, filing, and classification. It allows a full-text search of patents granted from 1976 to present, while patents granted from 1790 to 1975 can be found with a classification search. They can be viewed as images in the TIF format. The U.S. Patent and Trademark Office site also includes links to some international patent databases. 

The U.S. Patent and Trademark Office site also allows you to search for active and inactive U.S. trademarks using words or numerical descriptors and provides online images of trademarks that date back to the end of the 19th century.

According to U.S. common law, people can lay claim to a trademark they use. Trademarks don't have to be registered. This fact and the sovereignty that states have over chartered business entities and trade names makes a trademark search necessary before going through the process and cost of registering a trademark.

Too many people use a name without checking into their legal coverage, which creates larger issues and costs when they develop big marketing campaigns using names they can't legally use.

Performing a Comprehensive Search Study can help you decide if you have the ability to register your trademark. It's also a good idea to conduct this study before using a trademark for your business. If you use a mark another company is actively using, that company could dispute the use of the trademark and take the issue to court. 

A broad trademark search is the best way to begin, since there are so many unregistered or common law trademarks in the current market. Globalization also creates issues with using a trademark in an international market, and you'll want protection for your brand and your intellectual property.

A professional trademark search will find areas where your mark may overlap with existing trademarks. If you infringe on someone's existing trademark rights, you could face rejection or objection to your trademark application.

A preliminary trademark search is the first step to securing your trademark, since you'll be aware of similar existing trademarks before spending money and time on your application.

If you have trademark experience, you can use a free online resource, such as a Trademark Search engine, or the Trademark Electronic Search System, which is available through the U.S. Patent and Trademark Office and searches for existing marks that may be similar to yours.

You can also visit the Trademark Public Search Library between 8 a.m. and 8 p.m. at the Public Search Facility. This is located on the first floor of the Public Search Facility — Madison East at 600 Dulaney St. in Alexandria, Virginia. There may be a local Patent and Trademark Depository Library near you as well.

If you don't have much experience, you can consult a private trademark search firm, which will help you conduct your search for a fee, or you can hire a professional attorney. Trademark search firms can be found in the yellow page section of telephone directories. 

Unfortunately, a successful preliminary trademark search doesn't necessarily mean that your application will be approved. 

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Before you begin your search, define the class you want to register. 

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Find your class with the Trademark Class Search tool. This uses your product or service and tells you which class or classes you should register.

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Once you find your class, you can go to your country's Trademark Office and conduct a search there.

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Try different combinations of the name you're searching, so that you can identify any active trademarks that may be similar.

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Try different combinations of words and spellings of your trademark.

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Some countries don't have online databases, which means you will have to go to the local Trademark Office and ask for a list.

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If your mark is a design, you will need to search with a design code.

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Design codes can be found in a Design Search Code Manual.

If you need help with the U.S. trademarks database, you can post your legal need on UpCounsel's marketplace. UpCounsel accepts only the top 5 percent of lawyers to its site. Lawyers on UpCounsel come from law schools such as Harvard Law and Yale Law and average 14 years of legal experience, including work with or on behalf of companies like Google, Menlo Ventures, and Airbnb.