404 is something you have no control if some one tries <a href="http://http://<yousite&gt;.com/moron, and do not find a page then its not your problem.

But when crawlers try to access a genuine out link on your site and do not find the page, then it's a problem in your content. Every such instance devalues your site profile.

 

Hope this helps

Very well put.  I don't take corrective action on a 404 unless it is reported in Webmaster Tools or unless the Redirection plugin that I use lists an actual referring site, meaning that there is an actual link somewhere pointing to my site. 

But when crawlers try to access a genuine out link on your site and do not find the page, then it's a problem in your content. Every such instance devalues your site profile.

Hope this helps

broken links hurt your site. Remove them but this is just one of many factors influencing ranking. 

Based on what? They're not good from a user perspective, but Google themselves says that 404s won't typically harm your search results.

jonathangalt said:

I have about 70 URL errors from removing a bunch of tags and categories...will those errors affect the amount of impressions I get?

 

I'm not sure what to do to fix them though...

According to Google, 404 (not found) type errors don't typically affect search results. It says this somewhere on the page reporting those stats. They are mainly reporting them so you can improve usability.

ok, i'll try this app out for a bit to see if it works for me.  thanks guys!

I have about 70 URL errors from removing a bunch of tags and categories...will those errors affect the amount of impressions I get?

 

I'm not sure what to do to fix them though...

According to Google, 404 (not found) type errors don't typically affect search results. It says this somewhere on the page reporting those stats. They are mainly reporting them so you can improve usability.

I doubt that it would tie back to your impressions, but it's never a great idea to have loose ends, I've heard that it can affect page rank and other metrics.

I'm not sure what to do to fix them though...

It's also helpful if you can tell where those impressions were coming from and what articles they were visiting.

Is it normal for your impressions to make a huge jump up and return to zero?  I was regularly getting around 250 search impressions a day, now I'm getting 5 =(

They changed something again around the end of last month.  My impressions were 3,000 per day and dropped to 2,000 right around 9/28, the same time I know a lot of people saw a drop in traffic (sadly, I did as well).

That's a 33% drop for me, but if you dropped almost all your traffic, I would venture to guess that you were getting most of your search traffic from one or two search terms which got changed up when Google did their latest change.