In order to pass this test you must create and properly install a robots.txt file.
For this, you can use any program that produces a text file or you can use an online tool (Google Webmaster Tools has this feature).
Remember to use all lower case for the filename: robots.txt, not ROBOTS.TXT.
A simple robots.txt file looks like this:

User-agent: *
Disallow: /cgi-bin/
Disallow: /images/
Disallow: /pages/thankyou.html

This would block all search engine robots from visiting "cgi-bin" and "images" directories and the page "http://www.yoursite.com/pages/thankyou.html"

TIPS:

• You need a separate Disallow line for every URL prefix you want to exclude
• You may not have blank lines in a record because they are used to delimit multiple records
• Notice that before the Disallow command, you have the command: User-agent: *. The User-agent: part specifies which robot you want to block. Major known crawlers are: Googlebot (Google), Googlebot-Image (Google Image Search), Baiduspider (Baidu), Bingbot (Bing)
• One important thing to know if you are creating your own robots.txt file is that although the wildcard (*) is used in the User-agent line (meaning "any robot"), it is not allowed in the Disallow line.
• Regular expressions are not supported in either the User-agent or Disallow lines

Once you have your robots.txt file, you can upload it in the top-level directory of your web server. After that, make sure you set the permissions on the file so that visitors (like search engines) can read it.

In order to pass this test you must add an alt attribute to every <img> tag used into your webpage.
An image with an alternate text specified is inserted using the following HTML line:

<img src="image.png" alt="text_to_describe_your_image">

Remember that the point of alt text is to provide the same functional information that a visual user would see. Search engines, users who disabled images in their browsers and other agents who are unable to see the images on your webpage can read the alt attributes assigned to the image since they cannot view it.

Learn more about optimizing images for SEO.

Your two options for file compression are Deflate and GZIP.

• Deflate is an option which comes automatically with the Apache server and which is simple to set up.
• GZIP on the other hand needs to be installed and requires a bit more work to install. However, GZIP does achieve a higher compression rate and therefore might be a better choice if your website uses pages which have a lot of images or large file sizes.

Setting up file compression for your website will depend on which type of server you?re using for your website. Most likely, you?ll be using Apache, which means you can enable compression by adding a few deflate codes to your .htaccess file.

# compress text, html, javascript, css, xml:
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/xml
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript

For more advanced information regarding deflate you can check this Apache documentation.

In order to reduce the number of HTTP requests, you can use the HTTP Expires header to set an expiration time for your images or any other content type. You can add the following lines into your .htaccess file:

<IfModule mod_expires.c>
    ExpiresActive on
 
    ExpiresByType image/jpg "access plus 1 month"
    ExpiresByType image/jpeg "access plus 1 month"
    ExpiresByType image/gif "access plus 1 month"
    ExpiresByType image/png "access plus 1 month"
</IfModule>

In order to pass this test you must make your email addresses invisible to email spiders. Note that the best option is to replace your entire contact mechanism with a contact form and using the POST method while submitting the form. Other solutions are listed below:

• replace the at (@) and dot (.) characters
• replace text with images
• use email obfuscators
• hide email addresses using JavaScript or CSS trick