A "likelihood of confusion" is a trademark law concept that determines if consumers are likely to mistake one company's goods or services for another's due to similar trademarks, sound, appearance, or meaning, which could lead them to believe the products come from the same source.

It doesn't require proof that consumers are actually confused, but rather that there is a probable risk that an average consumer would be confused about the source, affiliation, or sponsorship of the goods or services.

In simple terms: Would a reasonable person think that the new product/service comes from the same company as, or is connected to, the well-known existing brand?

This is the most common reason for refusing a trademark registration, as the purpose of a trademark is to indicate the origin of products.

No Mechanical Test: There is no single rigid formula for determining a likelihood of confusion. Courts and examiners consider multiple factors, such as the specific circumstances of each case, to determine if confusion is likely. 

Key Factors Analyzed (The "DuPont Factors")

Courts and trademark examiners don't use a single test but weigh multiple factors. The most famous set comes from the U.S. case In re E. I. du Pont de Nemours & Co. While the list is non-exhaustive, the most critical factors are:

1. The Similarity of the Marks:
This is often the most important factor. The marks are compared in their sight, sound, and meaning.
Example: "Kronik" for energy drinks and "Chronic" for cigars were found confusingly similar in sound and appearance, despite the different goods.

2. The Relatedness of the Goods/Services:
Are the products sold through the same channels? Would consumers expect them to come from the same source?Example: Using "Apple" for computers and "Apple" for records would likely cause confusion. Using "Apple" for computers and "Apple" for a plumbing company probably would not.

3. The Strength of the Senior Mark:
Strong, distinctive, and famous marks (like "Google," "Kodak," "Xerox") are given a much wider scope of protection. It's easier to prove that a similar mark, even on unrelated goods, causes confusion because of the mark's "fame."

4. Evidence of Actual Confusion:
While not required, if you can show that consumers have actually been confused (e.g., misdirected customer inquiries, mistaken purchases, survey evidence), this is very powerful proof.

5. The Channels of Trade and Purchaser Sophistication:
Are both products sold in the same stores or to the same customers? Expensive goods bought by careful, sophisticated consumers (e.g., industrial machinery) have a lower likelihood of confusion than inexpensive, impulse-buy items (e.g., candy bars).

6. The Intent of the Junior User:
If the new user adopted their mark in "bad faith," knowing about the famous mark and intending to capitalize on its reputation, this strongly suggests a likelihood of confusion. The law assumes that a party intended the natural consequences of its actions.

Practical Examples

Likely Confusing:

• A new software company called "Micro-Soft" selling operating systems. (Similarity in sight/sound and identical goods).

• A new energy drink called "Pepsy." (Similar sound, related goods).

• A shoe company called "Nikke." (Intentional misspelling of a famous mark for closely related goods).

Likely NOT Confusing:

• A company called "Apple" selling actual apples from an orchard. (No relatedness of goods).

• A luxury car brand called "Dove" and a soap brand called "Dove." (Different markets, channels, and consumer expectations).

• A brand called "Delta" for faucets and "Delta" for airlines. (The marks coexist because the goods are unrelated and there is no consumer confusion about source).

In USPTO trademark filings, the “intent to use” (ITU) basis means that the applicant has not yet used the trademark in commerce, but plans to do so in the near future.

Here’s a breakdown:

Definition

Intent-to-use (ITU) filing basis is established under Section 1(b) of the U.S. Trademark Act (Lanham Act).
It allows you to reserve rights to a trademark before you actually start selling or offering goods/services under that mark.

Requirements

When filing an ITU application, you must:

• State that you have a “bona fide intention to use” the mark in U.S. commerce.

• Specify the goods and/or services you plan to offer.

• Pay the regular filing fee (same as for a use-based application).

You do not need to submit proof of use (specimens) at this stage.

What happens next

After the USPTO examines and approves the mark:

1. The mark is published for opposition.

2. If no one opposes it, the USPTO issues a Notice of Allowance (NOA).

3. You then have 6 months to file a Statement of Use (SOU) — showing actual use in commerce (with specimen and dates). You can request up to five 6-month extensions (total of 3 years from the NOA date).
   Filing Statement of Use (SOU) or 6-month extension requests involves additional fees.

Purpose / Intent

The intent-to-use system:

• Protects your priority rights as of the filing date (even before launch).

• Gives you time to develop, produce, or market your goods/services.

• Prevents others from registering a confusingly similar mark in the meantime.

Example

If you plan to launch a clothing brand “NORTHWIND” next year, but haven’t sold any items yet, you can file under Section 1(b) (intent to use).
Later, when your products go on sale, you’ll submit the Statement of Use showing the mark on the clothing labels or website.