However, using those default images and templates might make your presentation look unprofessional.
I RECOMMEND:- Check More Microsoft Power Point And Words Tips Here.

Google Images
Google Images is a huge repository consisting of literally millions of background images.
- First head over to Google images and choose your presentation topic.
- Enter some keyword related to your presentation niche and hit enter..
- Thousands of background images will be returned.
- In advanced search options, you can choose several options which include resolution, color and aspect ratios.
- You can also choose the license type, make sure you choose ‘Creative Commons’ licensed image, to avoid copyright infringement with commercial images.
- You can also search for a specific color, to allow the background image match with the theme of you’re presentation.
Using Royalty Free Image sites
There are several royalty-free vector and illustration sites where you could find thousands and millions of vectors for a small fee. You will not need to worry of any copyright infringement problems nor will you need to worry about scaling.
Templates Sites
There are hundreds of sites over the internet, which provide Free download of high quality PowerPoint Themes, Backgrounds, Illustrations, Graphs and a lot more. It is the best platform to find images, when compared to the other methods suggested above because it is completely free and are specifically designed and optimized for PowerPoint presentations.
Out of those, I personally prefer Slidehunter.com and FPPT, which do not charge any hidden charge, and totally free to download and use. The best feature they offer are free animated and 3D templates that work perfect for your presentations.
Author Bio:
Gautham is a expert designer, who shares tips at PowerPoint Templates for Download and PPT Tutorials.