If you are a PowerPoint user like me and are always looking for good and reliable resources to get assets for your slides without breaking the bank, then this is for you.

#1 Noun Project

(https://thenounproject.com/)
This is by far the most comprehensive website to source monochrome icons from. They have over a million curated icons at the time of writing and most of them are created by the global community. You can download icons in either png or svg format and you can download them in any color you want.
You can download them for free under a Creative Commons license, meaning you can download for free, but you must give credit to the creator according to the Creative Commons Attribution license.
If you want to use them without giving the creator credit, you can buy a monthly subscription for $9.99/month or annual subscription for just $39.99/year at the time of writing. There is no limit on how many royalty free icons you can download so it is really the best deal out there.
The have also developed aps for Illustrator, Photoshop, InDesign, Powerpoint, Word, Google slides, Google docs that let you download icons from within the software thus making it an integral part of your work flow.

#2 Freepik

(https://www.freepik.com/)
This is a one stop shop for sourcing graphic resources like stock photos, vectors, PSD files and color icons. This is a relative new website but is a fast-growing one. Like Nounproject, they use a freemium model which means, you can download for free but need to credit the author or pay for a monthly or annual subscription to use them without having to give any accreditation. Their monthly subscription costs $9.99 and annual subscription costs $89.99 at the time of writing. There is no limitation on number of downloads. With a paid subscription, you get access to all the content that free version offers but in addition, you can also download premium content, which is developed by the company itself. There is not a lot of compelling premium content yet, so you won’t miss out a lot if you did not have a subscription.
What sets them apart is that they offer vectors and PSD files at the same rate as any other content. If you have Illustrator or Photoshop, you can basically edit source files and suit them to your need without having to spend a lot of time.
If you do not have these software, you can still use the image version, but the real power of these assets is having the flexibility to edit them. All is not lost though if you don’t have Illustrator but still want to be able to edit vectors. You can use the free software Inkscape to edit the vectors or convert the original eps files to emf format using an online converter and use them in PowerPoint to get some ability to edit them. I can cover these in detail in a future post if there is enough interest.

#3 Flaticon

(https://www.flaticon.com/)
This is a sister site of Freepik that offers beautiful flat and colored icons based on the same freemium model. They have over 722,500 icons, of which about 159,000 icons are paid, and rest can be downloaded for free as long as you credit the creator. The costs for the premium icons is same as that for a Freepik subscription which makes it a little pricey.

#4 Cloudconvert

(https://cloudconvert.com/)
This not a resource for assets but a tool to convert files across different formats. This is a cloud-based file converter that is very fast, lightweight and above all, free. If you end up using Nounproject or Freepik, you would want the ability to convert svg files and eps files to emf file formats for getting more control over editing those in PowerPoint. Emf is a Windows vector graphics format which is like SVG format, so it gives you the ability to scale your graphics to any size without losing the quality and it also gives you the ability to edit them using native PowerPoint tools like Shape fill, Line color, Shadows and so on. One limitation of this site is that for the free version, if you convert too many files at once, it may limit you from converting more files for the day.
The website supports 218 file formats at the time of writing, so you can also use it for other purposes outside of PowerPoint.

#5 Skillshare

(https://www.skillshare.com)
This is a popular educational resource to take your slide design skills to the next level. Here you can learn the basics of graphic design, like layout and composition, navigation and hierarchy, typography, colors and so much more. Once you learn the concepts of design, you will never see the information in the same way. They offer a free 1-month trial after which you pay $15 for a monthly subscription or $99 for an annual subscription.