Late on Friday, Google unveiled its monthly list of algorithm changes, for the month of April. As usual, there is plenty to take in, with over 50 changes. Here are some observations we’ve made so far:

Google Algorithm Changes For April: Big List Released
Google Makes More Freshness Tweaks To Algorithm
Google Increases Base Index Size By 15 Percent
Bi02sw41: Did Google Just Make Keywords Matter Less?

Improvements in how Google handles spelling issues, seems to be a major theme from April’s list. Here are the relevant list entries related to spelling:

• Fewer bad spell corrections internationally. [launch codename “Potage”, project codename “Spelling”] When you search for [mango tea], we don’t want to show spelling predictions like “Did you mean ‘mint tea’?” We have algorithms designed to prevent these “bad spell corrections” and this change internationalizes one of those algorithms.
• More spelling corrections globally and in more languages. [launch codename “pita”, project codename “Autocomplete”] Sometimes autocomplete will correct your spelling before you’ve finished typing. We’ve been offering advanced spelling corrections in English, and recently we extended the comprehensiveness of this feature to cover more than 60 languages.
• More spell corrections for long queries. [launch codename “caterpillar_new”, project codename “Spelling”] We rolled out a change making it more likely that your query will get a spell correction even if it’s longer than ten terms. You can watch uncut footage of when we decided to launch this from our past blog post.
• More comprehensive triggering of “showing results for” goes international. [launch codename “ifprdym”, project codename “Spelling”] In some cases when you’ve misspelled a search, say [pnumatic], the results you find will actually be results for the corrected query, “pneumatic.” In the past, we haven’t always provided the explicit user interface to say, “Showing results for pneumatic” and the option to “Search instead for pnumatic.” We recently started showing the explicit “Showing results for” interface more often in these cases in English, and now we’re expanding that to new languages.
• “Did you mean” suppression goes international. [launch codename “idymsup”, project codename “Spelling”] Sometimes the “Did you mean?” spelling feature predicts spelling corrections that are accurate, but wouldn’t actually be helpful if clicked. For example, the results for the predicted correction of your search may be nearly identical to the results for your original search. In these cases, inviting you to refine your search isn’t helpful. This change first checks a spell prediction to see if it’s useful before presenting it to the user. This algorithm was already rolled out in English, but now we’ve expanded to new languages.
• Spelling model refresh and quality improvements. We’ve refreshed spelling models and launched quality improvements in 27 languages.

So, it sounds like Google will be attempting to correct more misspellings, while getting better at its corrections in general.

The one called “More spell corrections for long queries” was actually the one discussed in a video Google recently shared, showing an “uncut” look inside a search quality meeting. Remember that video, which showed a bunch of Googlers using Macs, discussing the algorithm?

“As you may recall, a couple months back we shared uncut video discussion of a spelling related change, and now that’s launched as well (see “More spell corrections for long queries”),” says Matt Cutts in the announcement of April’s changes.

It’s interesting that the change was in discussion all the way back in December, and didn’t go live until sometime in April.

Also in April, Google rolled out some misspelling improvements on the paid side of search, introducing new near match types.

“People aren’t perfect spellers or typists. At least 7% of search queries contain a misspelling, and the longer the query, the higher the rate,” Google AdWords Product Manager Jen Huang recently said.