Why three lines became a menu
A hamburger icon works like a compressed label: instead of showing several navigation choices, an app shows three short horizontal bars. The bars resemble a simplified list, and tapping them opens the items they stand for. The design trades immediate visibility for a smaller footprint.
That tradeoff matters on phones, where a row of links can crowd out the page itself. Hiding navigation behind one button leaves more room for the content, but it also adds a step: people must recognize the icon, open it, and then scan the choices.
The cost of hiding choices
The icon communicates that more options exist, but not what those options are. A visible label such as “Menu” is more explicit; a familiar three-line symbol takes less space. Designers therefore have to weigh compactness against discoverability—the chance that someone will notice and understand a control.
The choice affects more than appearance. If an important destination is tucked away, it may be less likely to be found than an option displayed directly on the screen. The hamburger menu is useful precisely because it conceals the list, and that same concealment is its limitation.
