11 Most Common On-Site SEO Mistakes

If you want to make sure your webpages rank well in search engines, it's essential to have a basic knowledge of search engine optimization (SEO). But the truth is, many people don't, so when they encounter SEO problems, they're a little bit stuck. SEMrush’s research shows that website owners often struggle with technical issues. That's no surprise because the average SEO checklist contains more than a dozen issues to address before a site can truly succeed.

But which SEO issues do you really need to focus on?

We decided to find out using real data. We have collected anonymous data on 100,000 websites and 450 million pages using SEMrush’s Site Audit tool to determine:

• top SEO problems

• how many sites these issues affect.

In this article, you will find a list of the most common on-page, technical SEO and website issues, and information about the way they can affect your search engine rankings. The infographic below summarizes our key findings, but you’ll learn even more if you read on.

Try SEMrush For Free

1. Duplicate Content

Google defines duplicate content as "substantive blocks of content within or across domains that either completely match other content or are appreciably similar."

According to our research, the most common SEO issue affecting websites is duplicate content, which we found on 50 percent of the sites we analyzed. During a recent Google Q&A session, Andrey Lipattsev, Search Quality Senior Strategist at Google, stated that there is no such thing as a duplicate content penalty. But that doesn’t mean it’s something you can just turn a blind eye to.

First of all, by having duplicate content on your website, you will lose your capability to choose which page you want to rank for. Search engines won’t know which pages you want to be considered landing pages in SERPs, and those pages can even start to compete with one another. Second, search engines are specifically designed to make the web a better place for users; valuable, unique content is highly appreciated by both search engines and users.

2. Missing Alt Tags and Broken Images

Images are an important part of content marketing, but they can also create major SEO issues. Our research concluded that 45 percent of sites have images with missing alt tags, and another 10 percent have broken internal images. Both of these are problematic.

Let's start with alt tags. They’re important to image search. Although search engines have gotten pretty clever, alt tags help them understand what images are about.

In other words, alt tags provide textual descriptions of images, which makes it possible for search engines to categorize them. That's one reason why your image alt tags should contain your SEO keyword phrases.

Alt tags are also useful for visually impaired people using screen readers, as the readers will use the information in alt tags to describe images to the web users. Search engines are very concerned about user experience, and images without alt tags can hardly be considered a sign that that a website provides value to the user. They can lead to a higher bounce rate and, as a result, they might be one cause of poor search engine performance.

Broken images cause the same issues as broken links, which we will look at in more detail below. Broken links are dead ends for users and search engines, and they can cause search engines to downgrade your website because they create a poor user experience.

3. Title Tag Issues

Search engines use title tags (page titles) to determine what pages are about. Title tags appear at the top of search listings, which means they also help web users decide whether to follow your link. Title tags are also one of the most important SEO elements on your page – correctly optimized title tags can really impact your rankings in a positive way.

At SEMrush, we have seen four major SEO problems related to title tags:

• Duplicate title tags affect 35 percent of sites.

• Overly long title tags impact 15 percent of sites.

• Missing title tags are problematic on 8 percent of sites.

• We found title tags that are too short on 4 percent of sites.

As mentioned earlier, Google always wants to deliver unique content to users. But missing and duplicate title tags don’t provide users or search engines with relevant information about a page’s content, nor do they communicate that a page provides value.

The length of your title tag matters because it affects how much of your title is visible in search results. According to the latest news, depending on the device that’s being used, Google may show 70-71 characters, so it's a good idea to keep the key information (including your chosen key phrase) within that range.

Most good SEO tools will help you to identify duplicate, long, short or missing title tags. For more help, check out our recent guide to optimizing title tags.

4. Meta Descriptions

Meta descriptions showing up in search results help web users decide whether to visit your site or not. Although meta description doesn't influence page ranking directly, the relevance of meta description influence page CTR, which is important.

Our research shows that 30 percent of sites have duplicate meta descriptions and 25 percent of sites have no meta descriptions at all.

Our Site Audit tool will help you identify both issues, but it's important to go in and fix them manually, if necessary. Again, if you are using WordPress, the right SEO plugin will help you set up rules to ensure that all your content has meta descriptions.

When you're ready to create new meta descriptions, here are some resources that can help you:

• 5 Dumb Mistakes That'll Wreck Your Meta Descriptions

• SEO Metatags Best Practices

• How to Create the Right Meta Description

5. Broken Internal and External Links

Broken links can be a big onsite SEO problem. As your site grows and you update resources, one or two broken links might not be a problem. If 404 page is properly set up, they’re not a problem at all, but what if you have hundreds of them?

This makes broken links a potential danger. There are several reasons for this, but, first of all, if a user sees a 404 page instead of the useful information they wanted, it causes a traffic dropdown. Also, users will perceive your site as low quality.

Second, broken links are a waste of your crawl budget. Each time search engine bots visit your website, they crawl a certain number of pages, but not your entire site. If you have a lot of broken links, you risk diverting the bots’ attention from your pages, which actually matters – your pages won’t be crawled and indexed.

Our research showed that 35 percent of sites we crawled have broken internal links that return bad HTTP status codes (70 percent of those return a 4xx - page not found or similar - code).

Twenty-five percent of sites we’ve analyzed had broken external links. In the long run, this issue can reduce the number of pages that will appear in the search engine results and impair page authority too, so it's something you need to fix.

You can always identify broken links via our Site Audit tool or a link checker plugin, and then fix all of them. You can also find broken inbound links and approach webmasters to suggest a new resource on your site they can link to.

6. Low Text-to-HTML Ratio

We saw the warning low text-to-HTML ratio on 28 percent of the sites we analyzed. This means that these sites contain proportionally more back-end HTML code than text that people can read. We suggest an acceptable lower limit beginning from 20 percent. Often, this warning is a sign of other SEO ranking issues you need to address. For example, a low text-to-HTML ratio can be a sign of:

• A poorly coded website (with invalid code and excessive Javascript, Flash and inline styling)

• Hidden text, which is something spammers do, so it's a red flag for search engines

• A slow site – the more code and script pages contain, the slower they’ll load, and page load is an important SEO factor.

Fix this issue by checking any pages on which this warning appears and:

• Removing unnecessary code to reduce page size and increase speed

• Moving inline scripts and styles into separate files

• Adding relevant on-page text where necessary.

Read More

If you want to study at SEMrush Academy for free, visit this link: SEMrush Academy