Have you noticed the new trend where people bold certain parts of sentences in a paragraph? Like this. It's everywhere: blogs, newsletters, and especially LinkedIn, where some posts are now so thoroughly bolded that the unbolded words feel like they should apologise for being there.
The theory is that bold text helps busy readers. The practice, mostly, is a paragraph yelling at you in random places. Let's break down when bolding helps, when it hurts, and what the research actually says.
Attention isn't the same as understanding
Yes, bold text grabs attention immediately, moth-to-flame style. That's exactly the problem. Every bolded phrase interrupts the natural flow of reading and forces a tiny decision: pause here? Is this the important bit? If you only read "certain parts of sentences", you don't get a complete idea. You get fragments wearing hi-vis.
The Nielsen Norman Group, who have been studying how people actually read since the 1990s, are blunt about this. Their guidance on formatting long-form content says bold should highlight critical information, sparingly, and warns directly: "do not bold just to strengthen your tone, as it can slow down scanning and cause confusion." Their rule of thumb is that highlighted text should never exceed about 30% of an article, and honestly, well before 30% you've just invented a second font.
Good writing means every word earns its place. If a sentence only works when half of it is bolded, the problem isn't the formatting. It's the sentence.
Readers don't like being told how to read
There's something subtly bossy about heavy bolding. Instead of letting readers find the emphasis through context, it force-feeds importance to particular words. The reading experience becomes mechanical and disjointed, like listening to someone who keeps grabbing your sleeve.
It's worth knowing your audience is mostly skimming anyway: Nielsen's classic study found 79% of users scan any new page, and only 16% read word by word. Scanners genuinely benefit from signposts. But the signposts that work are structural: clear headings, front-loaded sentences, short paragraphs, and the occasional genuinely key phrase in bold. When everything is a signpost, nothing is.
The UK government's style guide, which exists to make public information readable for everyone, goes even further than the usability folks: it bans bold for emphasis entirely, reserving it for interface instructions like "select Continue". If you want something to stand out, they suggest, restructure: front-load the sentence, use a heading, use a list.
A special word about fake bold on LinkedIn
Those chunky bold letters people paste into LinkedIn posts? They aren't bold text at all. They're mathematical Unicode symbols masquerading as letters, and to a screen reader they're gibberish. Accessibility specialist Per Axbom demonstrated that screen readers either skip the "bolded" words entirely or read them out character by character, so a blind reader hears your post with the most important words missing. They also break search and can render as empty boxes on older devices. As growth hacks go, "exclude people and defeat search" is a bold strategy in the worst sense.
When bold actually works
Writing evolves, and bold has legitimate jobs:
- Headings and subheadings. Their natural habitat.
- Short, genuinely key phrases. One per section is plenty, and it should make sense read alone.
- Interface instructions. "Click Submit" is bold doing honest work.
- Skimmable lists. Like this one, where the bold lead-in tells you whether to read the rest.
The golden rule
Here's the simplest test we know: if you have to read it twice, it isn't working. If your eyes ricochet around a paragraph chasing bolded fragments and you lose the thread, the formatting is making reading harder, not easier.
Our job as writers is to create content that's engaging and easy to read. Bold is a tool, and like most tools it works best when you can barely tell it's been used. Use it with intention. (See? One per post is plenty.)