We all misspell words when we type in search boxes and we expect the search software to be able to know what we meant and produce the results we are looking for, this is called ‘fuzzy searching’.
If you search for ‘website design’ it will return matches for ‘website design’ but what if you made a mistake and entered ‘wesite design’ or 
‘website deisgn’ or used variations such as ‘website design software’? Fuzzy searching will take care of this and your website developer should programme your search box to figure out what you actually meant as opposed to what you really typed.
But, not all search systems work this way and will take your search words quite literally. If the search software doesn’t take fuzzy searching into account you could be misled into thinking there are no results for your searches, when there are.
Thankfully, Google is very good at fuzzy searching and can interpret spelling errors, capital letters and different ways of spelling words i.e. colour and color. If your website has a search facility make sure it is able to handle fuzzy searches, otherwise your visitors might not be able to find anything on your site.