Letterboxing is a privacy feature available in browsers like Tor and Firefox, designed to obscure browser dimensions by adding gray bars around the web view, thereby making it harder for advertisers to track users through browser fingerprinting. Introduced in Tor in 2015 and Firefox in 2019, letterboxing adjusts the browser window dimensions to be multiples of 100 or 50 pixels, reducing the uniqueness of screen sizes used for identifying browsers. Browser fingerprinting, which collects data such as screen resolution, operating system, and browser version to create a unique identifier, is commonly used for fraud detection and user protection. While letterboxing can make it easier to reset simplistic fingerprinting identifiers by masking true screen dimensions, sophisticated solutions like Fingerprint Pro use a combination of client-side and server-side signals to maintain a stable identifier even if some signals change, making simple letterboxing ineffective against advanced fingerprinting techniques. Despite its limitations, letterboxing represents one of several strategies to enhance online privacy, as browsers increasingly adopt anti-fingerprinting measures amidst rising privacy concerns.