As you can see, it gives the show name 'No Game No Life', and the character 'Jibril'. Here is what the results for ex.1 should be. If it is an often used reaction image or meme occasionally you will only get more results pointing to meme sites or tumblr pages. Google will generally give you the name of the character or show for most images, depending on the image.

Generally it is easier to copy and paste an image url. You can choose to either upload the image url, or the file if you have it saved. Google Images: Here is a little gif to show the different options. I will be using this as ex.1 and this as ex.2 to show the strengths and weaknesses of certain reverse searches. TL DR at the end if you would rather not read all the details. Also, for Chrome users, pressing 's' after right clicking on an image will reverse search it through google for you. There are also useful plugins for Chrome and Firefox that let you access the reverse searches with a simple right click.

They all do different things, so depending on what you are looking for a certain site may be better to use than others. The most useful and relevant reverse image searching sites are Google Images, trace.moe, SauceNao, IQDB and Tinyeye.

Image finder