Good mobile web design is essential in today’s world.

What Makes Good Mobile Web design ?

Google and AnswerLab conducted a research study to answer this question.

Mobile users are very goal-oriented. They expect to be able to get what they need, immediately, and on their own terms.

The study was held through 119 hour-long, in-person usability sessions with participants in the US. Participants were asked to perform key tasks across a diverse set of mobile sites. iOS and Android users were included, and users tested the sites on their own phones. For each site, participants were asked to voice their thoughts aloud as they completed conversion-focused tasks like making a purchase or booking a reservation.

The study uncovered 25 mobile web design principles, grouped into five categories.

Home page and site navigation in mobile web design

Success: Focus your mobile homepage on connecting users to the content they’re looking for.
Keep calls to action front and center
Make secondary tasks available through menus or “below the fold” (the part of the webpage that can’t be seen without scrolling down).

DO: Make all of your users’ most common tasks easily available.

DON’T: Waste precious above-the-fold space with vague calls-to-action like “learn more”.
Keep menus short and sweet

DO: Keep menus short and sweet.
Mobile users don’t have the patience to scroll through a long list of options to find what they want. Reorganize your menu to use as few items as possible, without sacrificing usability.

Make it easy to get back to the home page

DO: Make it easy to get back to the home page.
Users expect to go back to the homepage when they tap the logo in the top-left of a mobile page, and they become frustrated when it isn’t available or doesn’t work.

Don’t let promotions steal the show
Large app install interstitials (e.g., full-page promotions that hide content and prompt users to install an app) annoy users and make it difficult to perform tasks. In addition to annoying users, sites that use interstitials may see a negative impact to their search rankings.

DO: Promotions should be easily dismissable and not distract from the experience.

DON’T: Interstitials (sometimes called door slams) often annoy users and make using the site a pain.
Site search
Success: Help mobile users find what they’re looking for in a hurry.

Make site search visible
Users looking for information usually turn to search, so the search field should be one of the first things they see on your pages. Don’t hide the search box in a menu.

DO: Make search visible

DON’T: Hide search in overflow menus
Ensure site search results are relevant
Users don’t scan through multiple pages of results to find what they’re looking for. Make life easier on users by auto-completing queries, correcting misspellings, and suggesting related queries. Rather than reinventing the wheel, consider robust products like Google Custom Search.

DO: Macy’s only returns kids items.

DON’T: Return results for anything with the word kid in it.
Implement filters to narrow results
Study participants rely on filters to find what they’re looking for, and abandon sites that do not have effective filters. Place filters above search results, and help users by displaying how many results will be returned when a specific filter is applied.

DO: Make it easy to filter.

DON’T: Hide filter functionality.
Guide users to better site search results
Zappos guides users by asking them what they’re looking for.
DO: Help users to find what they’re looking for by guiding them in the right direction.
For sites with diverse customer segments, ask a few questions before presenting the search box, and use the customer’s responses as search query filters to ensure that users get results from the most relevant segment.

Commerce and conversion
Success: Understand your customer journeys and let users convert on their own terms.
Let users explore before they commit
Study participants were frustrated by sites that require upfront registrations to view the site, especially when the brand was unfamiliar. Although customer information may be integral to your business, asking for it too early may result in fewer registrations.

DO: Allow users to browse the site without requiring sign in.

DON’T: Place login or registration too early in a site.

Article from Web Fundamentals >
What Makes a Good Mobile Site? by Jenny Gove on Google