How does google detect if page has been update

I was wonering how does google detect if a web page has been updated or changed ?

is it by page size or does google just checks the server log ?

 

File timestamp and of course on-page copy. If you submit a sitemap it would include the lastmod tag in the xml.

 

so if i just add say for example one letter to the page and then upload it, will google take that as a chnage ?

the reason is google crawls my page but does'nt update the title tag or discription in its index, its always the old title and discription

 

Of course .

So you need to submit an XML sitemap to Google and specify your own parameters, like update frequency etc...

 

in some time limit google visit your website for index and and then check your website is update or not. and other way is that when we are submit sitmap in google webmaster tool then google visit our website for index then it will find website is update or not.

 

When Google crawls your site, it will check the last time your server was updated and match that to the lasttime it was updated, this lets Google know the page has been updated, it may also match what it has in its cache and see if your page has changed. Best way is to upload a sitemap everytime you update

 

If your server is properly configured for conditional get requests in the response header it will tell the spider if the page has been modified or not.

 

For a blog, hosted using wordpress software, there is an auto pinging facility which automatically pings various search engines whenever an update takes place....No wonder, wordpress software is considered very SEO friendly...

Regards,

RightMan

 

You can create xml site map then submit to webmaster tools, when spider is crawl your pages then SE takes that as a changes.

 

sitemap is very useful for this purpose.

 

Iam updating our website in 2 days. Will google catch my pages automatically or is there something i must do with it.

 

Whenever a change is made there is a change in time of updation. Change in time is being detected by the google server and ofcourse we cannot neglect the sitemap, it also help in detecting it.

 

Whenever a change is made,there is a change in time of its updation. Change in time is being detected by the google server and ofcourse we cannot neglect the sitemap, it also help in detecting it.

 

through sitemap or when google bot crawl pages then they can detect.

 

I think there is some confusion amongst the people asking the questions and the people answering. I believe what the people ASKING want to know. Is how does google know you have updated your site WITHOUT visiting it. The answer is they dont.

Its not as though when you update your site, google automatically knows. You update your site, and then THE NEXT TIME google crawls it, it will know you updated. If everytime google comes crawling back, it finds updates, then it knows you are a good source of info etc.

 

I m Updating my sitemap and also changing my content. I do not feel any help from sitemap bcz after update sitemap taking long days to update/crawl my site. So if update regularly google will slowly start to increase crawl rate