Instead of saving images from Internet to your computer and then uploading them to your blog, now while writing post you can save images directly from URL to your blog and use them inside your posts.
When you have to show other website images in your posts then what you normally do is save those images in your computer then upload them in your site’s media library. But now you can reduce these steps and save time.
Remote Images Grabber is a free WordPress plugin by Andreyk. It fetches images from given URL or from a piece of html-code and saves them directly to your blog’s media directory, and attaches them to the appointed post. Install and activate it, then visit Dashboard -> Media -> Image Grabber and add the URLs of images you like to save in your website. You can also use it while writing your posts, using its tab your post editor’s upload box as shown in the image.