How google recognises 2 words without spaces?

I want to understand how google handles no space between 2 words. For example there are 2 words - word1 and word2. I write in search box 'word1word2', it says do you mean 'word1 word2' or just understands to look for 'word1 word2'. Any information what data structure and algorithm they use? I see in this answer How to split text without spaces into list of words?, it is suggested to use trie data structure.