While overall web activity decreased slightly in April, YouTube increased U.S. visitors over the prior month, with average visitors spending 2.9 percent more time on the website in April. Visitors to AOL’s network of sites also spent more time on average, about 5 percent longer during April.

While 194.8 million Americans went online in April, overall Internet use is down 2.4 percent from March. Not surprisingly, with the shorter month U.S. consumers spent slightly less time online on average (-3.8%) in April, and visited fewer unique sites compared to the month prior. Despite the slight monthly decline in time spent, Nielsen estimates that Internet access at home and work grew to 244 million individuals in the U.S. during April 2011.

Yahoo! followed Google and MSN/Windows Live/Bing Search with a 13.1% share of U.S. searches, falling from a 14.3% share in July 2010 (a 1.2% delta decrease or an 8% relative decrease).

In terms of a year-over-year comparison, Google has seen little change in its share of search while Yahoo! has seen a small but steady decline, going from a 16.0% share to 13.1% (a delta drop of 2.9% or a relative drop of 18%). MSN/Windows Live/Bing’s share has grown from 10.7% in August 2009 to 13.9% (a delta increase of 3.2% or a relative increase of 30%).

Microsoft and Yahoo announced a search deal in July 2009 where Microsoft would start powering Yahoo! Search while Yahoo! became the exclusive worldwide relationship sales force for both companies’ premium search advertisers. Microsoft Bing officially started powering part of Yahoo! searches starting in August 24, 2010. If we combined Bing-powered search in August pro-forma, it would represent a 26% share of search.

Nielsen only reports on search queries generated by a user, hence contextual searches or hovers or in-text searches are not reported.

Yahoo! followed with 14.3% share of U.S. searches while MSN/Windows Live/Bing held a 13.6% share. Both engines experienced a slight relative increase in Month-on-Month share (2% and 4%, respectively). Together these top three engines account for more than 9 out of 10 searches (92.1%).

In terms of a Year-on-Year comparison there has been little change in Google’s share but more significant movement amongst its closest competitors.

MSN/Windows Live/Bing’s share has grown from 9.0% to 13.6% (a delta increase of 4.6% or a relative increase of 51%) while Yahoo!’s share has fallen from 17.1% to 14.3% (a delta drop of 2.8% or a relative drop of 17%). Consequently, over the last year Yahoo!’s delta lead over MSN/Windows Live/Bing has been reduced from 7.1% to only 0.7%.

The number of searches conducted in the U.S. over the last year has decreased by 16% from 10.5 billion in July 2009 to 8.8 billion in July 2010. MSN/Windows Live/Bing was the only one of the top three engines to have experienced an increase in search volume – a 28% increase from 0.9 billion to 1.2 billion.

Nielsen counts and reports explicit searches only. Nielsen does not count contextual searches.

Although Yahoo (13.7% share of U.S. searches in June 2010) remained ahead of MSN/Windows Live/Bing (13.4%) the gap was less than half what it was in May 2010, when Yahoo! had 13.8% share compared to 13.0% for MSN/Windows Live/Bing.

Between them the top three engines account for 92.0% of all US searches in June 2010 – a slight increase from 91.8% the previous month. Factoring in AOL and Ask means the top five engines account for 96.1% market share – up from 95.9% in the previous month.

Year over Year Comparison
The last year, as with the month-on-month change, has seen little change in Google’s share but much more significant movement amongst its closest competitors.

Google’s share of the U.S. search market over the last year has dropped from 66.1% to 65.0% (a delta drop of 1.1% or a relative drop of 2%).

In the same period, Yahoo!’s share has fallen from 16.2% to 13.7% (a delta drop of 2.6% or a relative drop of 16%) whilst MSN/Windows Live/Bing’s share has increased from 8.9% to 13.4% (a delta increase of 4.5% or a relative increase of 51%). Consequently the difference in share between Yahoo! and MSN/Windows Live/Bing has shrunk from 7.4% to 0.3%.

In June 2009 the top five engines accounted for 95.9% share of all US searches just as they still did 11 months later in May 2010.

Nielsen does not count contextual searches.

Between them the top three engines account for 91.8% of all US searches. Factoring in AOL and Ask means the top five engines account for 95.9% market share.

Searches represent the total number of queries conducted at the provider. Example: An estimated 6.4 billion search queries were conducted at Google Search, representing 65.7 percent of all search queries conducted during the given time period.

Note: MegaView Search data – including total searches, unique searchers, search share, and all other search figures – cannot be trended with search results prior to October 2009 due to recent methodology changes.

Example:  The data indicates that 62.3 million home and work Internet users visited at least one of the Wikimedia Foundation-owned sites or launched a Wikimedia Foundation-owned application during the month, and each person spent, on average, a total of 15 minutes and 21 seconds at one or more of their sites or applications.

The parent level is defined as a consolidation of multiple domains and URLs owned by a single company or division. The brand level is defined as a consolidation of multiple domains and URLs that has a consistent collection of branded content.

Example:  The data indicates that 67.3 million home and work Internet users visited at least one of the Wikimedia Foundation-owned sites or launched a Wikimedia Foundation-owned application during the month, and each person spent, on average, a total of 13 minutes and 51 seconds at one or more of their sites or applications.

The parent level is defined as a consolidation of multiple domains and URLs owned by a single company or division. The brand level is defined as a consolidation of multiple domains and URLs that has a consistent collection of branded content.