In order to work properly, autocomplete uses a number of different things to predict what you're going to search for. If it didn't look at these patterns and habits, the program would essentially be grasping at straws and figuring out what you want. Instead, it looks at four main criteria to get the responses that it thinks you're looking for:
Google, for example, already knows where you're located. It can use the permissions that it already has obtained to determine where you're at. How does this help autocomplete? Well, the search engine knows what people in your area have been looking for, and is aware of any large new stories that are happening in that geographical area.
For example, the system can sense that someone searching for "is insert-cable-provider down right now…" and would fill in the last few words with your general location. It also knows if anyone else is searching for that same string of words; therefore, it can ascertain whether or not others might be having the same issue.
In addition to this, the system notes that people in certain areas tend to look up the same things, so it can predict that you just might be like everyone else in your state, county, city, or general location.
The Language You Use
By looking at the language you've used in the past, the system knows how you phrase things. Someone who searches for "restaurant near me in Cleveland" will use a similar phrase to look for a "pet store near me in Cleveland."
Search engines know that people tend to have the same writing habits, which don't change over time. Some people use shortcut words, others prefer to use the same slang repeatedly, and in general, users searching for things will use very similar language time and time again.
This also includes writing in languages other than English. If you commonly use French or Spanish to write your searches, AI-powered search engines will notice that autocomplete will fill in the blanks accordingly.
Any Past Searches That You've Made
In addition to knowing how you tend to phrase things, autocomplete also has access to previous searches that you've made.
If you've spent the last half hour looking for small business bureaus in various cities to fill in a spreadsheet for work, the system will start to fill in the next searches for you.
You won't have to type in "name of city small business organization." Instead, you'll just need to enter the city's name and watch the predictive text do the rest before pressing the search button. This saves you plenty of time.
Any Current Trends
On top of everything else that autocomplete uses to determine what you're going to search for, the system also stays on top of any current trends.
These can be anything from large news stories, like a dangerous storm, or things like election news, or events that are going on either in the country as a whole or in a certain geographic area. If the news is large enough, search engines assume that people are going to be doing searches on it, so autocomplete is ready to accommodate them.