Last year, Google tested a more personal approach for YouTube in the Android app, rolling out a new design with topic filters that helped you trim down recommendations based on content. Following a wider rollout of the feature in the Android app, Google has now decided to expand it to the iOS app, and even YouTube on the web/desktop. Previously it was only available in English, but it will be expanding to French, Portuguese, and Spanish as well.
The change includes a slight redesign of the Home pane for YouTube on desktop/web, with a new topic bar/ribbon you can scroll through just above your recommended videos. Those topics will be personalized to your recommendations, based on the company's existing suggestions and user profile. You'll also get topics in the "Up Next" list (the list that appears to the bottom right on desktop/web when you're watching a video), which may be related to the current video's topic or your general recommendations.
More personalized topics/categories are also planned for later in the year, pending feedback.
The new feature is rolling out over the next couple of weeks, according to YouTube, so if you don't see it on your account yet (we don't), it might take a little longer to land.