That snippet is very useful to increase CTR (Click through rate), or the Click opportunities of link you share. The snippet gives brief information about the web page shared. Therefore, you have to make it interesting and make peoples curious so they click it.
You may think that it is loaded automatically and cannot changed. When in fact you can set the thumbnail image, descriptions, even the title as needed. The trick is to equip the web page you shared with the html code below :
To set title
<meta property = "og:title" content = "Your custom title here" />
To set snippet description
<meta property = "og:description" content = "Your custom snippet description here " />
To set the thumbnail image
<meta property = "og: image" content = "path-url-of-your-custom-thumbnail-image-here"/>
The three code above placed in <head> tag like other <meta> tag.
But, if you are using CMS like wordpress or blogger, It is impossible to include the code manually on each pages. Therefore, you need additional coding or plugins in order that markup is automatically added to each page.
If you use Self-Hosted WordPress, you can use the plugin WP Facebook Open Graph protocol to automate it.
Whereas if you use Blogger, you can follow the following ways:
1. Go to Blogger Dashboard > Template > Edit HTML
2. After being shown the html editor, enter the following code above the </ head> or between <head> and </ head>.
<meta expr:content='data:blog.postImageThumbnailUrl' property='og:image'/>
<meta content='https://lh6.googleusercontent.com/-Gqxzyx1D-qM/Sd6gUSMyvxI/AAAAAAAAAIA/67EBdl4ZQ2k/w354-h472-no/Holland1.jpg' property='og:image'/>
<b:if cond='data:blog.metaDescription != ""'>
<meta expr:content='data:blog.metaDescription' property='og:description'/>
<meta expr:content='data:blog.pageName' property='og:title'/>
<meta content='URL to default image for homepage you want' property='og:image'/>
Okay, That’s all. Hope you are helped with this. Feel free to ask in comment if you have some trouble.