Editor's note: Check out our new ebook, Introduction to Search Engine Optimization , for updated information for 2011!   Click here to download .

Last week we held a webinar on the basics of Search Engine Optimization (SEO) as part of our ongoing HubSpot webinar series. (If you missed any of our webinars, be sure to check out our marketing webinars page for all our archived presentations.)

We had to pack a lot of info into this short one-hour webinar so unfortunately we didn't have a chance to answer all of the questions we received.  Here are some of your top questions from last week's SEO webinar with answers and links to more information.

How does using flash on a website affect SEO?

The quick answer is that flash is bad for SEO.  In a previous post, we dubbed using flash for your entire website as the #1 Most Egregious SEO Mistake . This is because search engines see the entire flash presentation as one big image and it can't index all the content that, though visible to humans, is not visible by search engines.

If my website uses frames, will search engines be able to see all of my content?

Using frames is almost as bad as building your website in flash because with frames, too, search engines cannot index your content.  Any content displayed within a frame on a website cannot be crawled or indexed by search engines.

How do password-protected sites or content behind login forms do in terms of SEO?

Search engines will index content as long as they can access it - if you have content behind a secure login page, search engines see that as a dead end and will not be able to index that content. That content does not help you in terms of SEO.

What is the impact of hidden tags or hidden content on your site (visible in the code of the site but invisible to humans)?

Hidden tags or content do not have much influence in terms of your search engine ranking . Furthermore, do not use hidden content as a way of tricking search engines into indexing your website for keywords not naturally used on the page. In general, on-page SEO techniques such as these do not weigh in as much as off-page SEO factors.

Is it better to use a subdirectory instead of a subdomain for blogs or verticals?

There is a bit of a debate about whether or not this matters anymore. In general, either is fine - as long as you own and control each of your website URLs. There's a bit more about using a subdomain or subdirectory in our previous post on Launching a Business Blog .

What are some good tips for building inbound links? Should I try to get reciprocal links?

Inbound links are definitely key to ranking well in search engine results. Check out our Introduction to Search Engine Optimization ebook for link-building tips. Steer clear of link-building opportunities that involve reciprocal links - this is a known black hat technique.  For more, read our previous post, Silly Rabbit, Tricks are for Black Hat SEOs .

How important is Google PageRank in determining position in Google search results (organic and PPC)?

Google PageRank is a measure of Google's understanding of your website's quality.  PageRank is calculated based on a number of different factors (inbound links playing a huge role) and is one key in how you rank in search engine results.  Read more in our ebook, An Introductory Guide to Paid Search .

How does the number of pages on your website affect your ranking in search engines?

Search engines like fresh content and more of it.  Search engine web crawlers will visit your site periodically and look for new content to index. The more (unique) pages you have, the more content for the search engines to index, which helps you rank better. Learn more from our Introduction to Search Engine Optimization ebook, and check out our free SEO tool WebsiteGrader to find out how many pages of your website Google has indexed.

Is it important to submit your site to search engines and directories online?

It is no longer necessary to formally submit your site to search engines - they will naturally find and index your site. Directories can make for good linkbuilding opportunities, but be selective - don't submit your site to low-quality directories that are more link-farms than high quality resources. Here is a list, for example, of some high quality blog directories where you can build links to your website.

What is the right number of keywords to target for a given website page?  What is too many?  Too few?

Generally, you want to target 3-5 keywords per page of your site, so the total number of keywords you target depends on the number of pages of your site.  Blog articles are also great opportunities to target long-tail keywords not otherwise on your site.  Here are some more detailed keyword tips . 

How do you balance your PPC campaigns with your organic SEO campaign?  How do you get started and evaluate the value of a PPC campaign versus your organic SEO efforts?

There is a lot we could say about organic search vs. paid search marketing campaigns. First you should understand why SEO is better than PPC as a long term strategy, and when and how to launch a PPC campaign. Check out our ebooks, Introduction to Search Engine Optimization and An Introductory Guide to Paid Search , for more information.

Have any more questions?  Leave a comment!