Its because of the good search results they give and they are efficient. And + they are always scanning the net for new stuff.
google is #1 because it returns the best results and does it FAST. I remember when I first tried google, I was skeptical, cause the name sounded lame, unlike yahoo or altavista. but then using it a few times, it was clear i was finding what i wanted everytime i searched just once, and then they are always returning me search results as quick as 0.000000000009 seconds. RIDICULOUS
They also started rather early in the internet's live so they have had a great head start which goes for the same with Yahoo.
It just gave more useful results then other search engines While for example altavista was full of spam yahoo was indexing much less then Google.
best search results, simple and friendly, and with all of inovations and integrations in the past 2-3 years it will stay no.1 fora long time to come
I started using google from around 2000 earlier used to search with alltheweb, and mamma (thats what i think it was )use it mainly because of 1) simple layout ( msn and yahoo took ages to load when I was on dialup) 2) relevant search results never looked back ever since
Google results for sure. They are way more accurate and targeted to what are you searching for most of the time.
Google home page has a simple interface. Also compared to Yahoo & MSN, Google indexes very fast. Google started as a search company and devoted its entire time to improve the search results.