A logo isn’t an image, it’s a family of files. Without the right ones, it comes out blurry on a sign, dull in print or unreadable in a browser tab. A logo’s master file is vector (SVG, PDF, EPS or AI): it scales without loss, from a business card to a storefront. Each colour exists in several recipes: RGB for screens, CMYK for print, often a Pantone reference. A logo needs variations: horizontal, vertical, symbol only, versions for light and dark backgrounds. For Google, the favicon must be square, and preferably larger than 48 × 48 pixels. Vector or pixels: the difference that matters A raster image (JPG, PNG, WebP) is a grid of pixels. Enlarged beyond its original size, it becomes blurry or jagged. A vector image (SVG, PDF, EPS, AI) describes shapes with points and curves: it redraws itself sharp at any size. A logo’s master file must therefore always be vector. It’s the one you send to the printer, the sign maker, the embroiderer or the engraver. A logo delivered only as a JPG is a logo that will have to be redrawn the day it has to go on a storefront or a vehicle. The ten-second test Open the file and zoom to 800%. If the edges stay sharp, it’s vector. If they turn into staircases, it’s a pixel image, and you’re missing the source file. One format per use SVG: the web’s vector format. Light and sharp on every screen, it drops straight into a website. PDF, EPS or AI: the vector formats of print and design software, the ones printers ask for. PNG with a transparent background: for all uses where vector isn’t accepted, such as office documents, presentations or some platforms. JPG: only when a solid background isn’t a problem, for example a profile picture. It doesn’t handle transparency. RGB, CMYK, Pantone: one colour, three recipes A screen makes its colours with red, green and blue light: that’s RGB, which the web often writes in hexadecimal. A printer makes them with cyan, magenta, yellow and black inks: that’s CMYK. The two systems don’t cover the same colours, and some very vivid reds or blues on screen simply don’t exist in four-colour print. Serious brand guidelines therefore give each colour in both systems, adjusted to look as alike as possible, and often a Pantone reference: a premixed ink, used when the colour must be exactly the same from one medium to another, on packaging, textiles or objects. The variations you’ll need A single logo doesn’t fit every space. The same mark has to work as a website banner, as a square on Instagram, tiny in a browser tab and huge on a truck. a horizontal version and a vertical, or stacked, version; the symbol only, for square formats and very small sizes; a version for light backgrounds, one for dark backgrounds, and a single-colour version for engraving, stamps or marking; usage rules: the clear space to leave around the logo, its minimum size, and what not to do (distort it, recolour it, add a shadow). Logos are exempt from contrast rules, not from legibility Web accessibility rules (WCAG) require a contrast of at least 4.5:1 between text and its background, 3:1 for large text. They explicitly exempt text that is part of a logo. That’s no reason to skip it: a logo you can no longer make out on a dark background no longer does its job. The favicon, the small format people forget The favicon is the small icon that shows in the browser tab and next to your website’s name in Google results. Google requires it to be square, at least 8 × 8 pixels, and recommends a size larger than 48 × 48 pixels. It accepts formats such as ICO, PNG, GIF and JPEG, and requires a stable address its crawlers can access. The full logo almost never fits. It’s the symbol alone, or an initial, that has to stay legible there. Hence the value of designing that symbol from the start, rather than shrinking the whole logo until it no longer looks like anything. What to check at delivery The vector source files, with a PDF or SVG that opens without the designer’s software. Each variation as SVG, PDF and transparent PNG, in light, dark and single-colour versions. The colours in RGB, hexadecimal and CMYK, with the Pantone reference if there is one. The fonts used and their licences: a font bought by the designer for their work doesn’t necessarily cover your own use. A usage guide, even a short one, and a contract assigning you the rights to use the logo: that’s what lets you use it freely, evolve it and register it as a trademark, with OMPIC in Morocco or INPI in France.