Here is a blog post you can use to discuss this font and how to legally acquire it.
Impact was designed by Geoffrey Lee in 1965 to be the ultimate attention-grabber. Its "deep" impact comes from: Minimal X-height/Counter space
Unlike the standard version bundled with Windows, is typically a commercial product.
A: Anton (from Google Fonts) is the closest match. Bebas Neue is slightly narrower, while Oswald is heavier.
Because the letters are naturally wide, tight kerning can cause letters to bleed into each other. Use your design software's "Tracking" tool to add a little breathing room (+50 to +100) for readability.
Before downloading any "free" font: