What is Google +1 Button?

Google +1 button is an option that Google provides to recommend the site or article by a person to his/her friends. The buttons are created in two ways:
1- Google itself provides +1 button next to google search results. By clicking on the button, one endorses the web link for quality content. It helps to bring human recommendation to the search results.
2 – A website owner can integrate Google +1 button on the website home page or any other pages. By doing so, website provides an opportunity for users to recommend the website or link to their network. It helps websites to get good ranking on google search results.

The Google +1button can be integrated in to websites, pages and blogs. Currently, Google does not offer it for mobile search results.

Google has made adding +1 button to the websites, particular pages or blogs very simple. One can add +1 button to their websites or blogs by just copy pasting small code in to the website. Google offers +1 button in four sizes:
Small (15px)
Medium (20px)
Standard (24px)
Tall (60px)
There is an option to either use buttons that show the count of +1s or the button without the count.However, the tall button icon always displays number of +1s.
The button and annotations are currently available in 40 languages

Google offers the facility of tracking all +1 button interactions with google analytics.

Recent statistics show that Google +1 plugins are fast moving up the ladder in the adoption of social plugins by top websites across the world. Google +1 button is currently second most popular plugin implemented on top websites. The first being facebook “like button” and “like box”, with more than 10 percent, Google +1 button is present in nearly 5 percent of the top 10,000 websites.