You can use .html, .htm, .asp, .php, etc as your URL file extension.
I wanted to ask if search engines prefer one of these over others.
Thanks in advance !
No. The file extension absolutely does NOT matter.
But, one thing you can do to improve SEO results is to include the targeted keyword into the file name while user underscores.
For example: yoursite.com/targeted_keyword_here.html
"targeted_keyword_here.html" is the file name.
Yes, I know about the "underscore" Vs. "dashes" war that has been going on by SEO people for years..
I have came to the conclusion that underscores are better... so, I'm an "underscore" guy..
...but, I would not be surprised if a "dash" SEO person commented here though...
Here's the main reason I usually use underscores:
Dashes are used in the English language in some words.. as proper English. And, there are not ANY words in English that are connected with underscores.. so, using dashes has a chance of confusing the SE bots..
It makes no difference but using dynamic extentions such as .php, .asp/x and then having a long query after the extention can cause some issues.
If you go down that line have a look at using .htaccess or some sort of friendly URL options.
Go with .htm or .html, a lot of search engines don't handle other url extensions very well. Google even openly talks about avoiding .php because of its tendency to add ?'s to the url. HTML is by far the cleanest and most readable coding language for search engines so definitely use it when you can.