Software
Microsoft PowerPoint is the most commonly used software for creating posters.
Apple Keynote, Adobe Illustrator, and free/open software options such as LibreOffice Impress and GIMP (GNU Image Manipulation Program) can also be used to create academic posters.
Size
Most conferences and meetings have size/dimension requirements. The most common sizes are 36” tall x 48” wide (horizontal or “landscape” orientation), although other sizes are also typical.
Quick Response (QR) codes can be used to link to external resources such as an electronic version of your poster, supplemental materials, an academic paper, a personal or lab webpage, a survey, your contact information, etc.
Use your smartphone camera to scan it - a link should automatically open. QR codes should be at least 5" x 5" large on your poster.
Paper Poster
Usually the cheapest option, quick turnaround, but can be cumbersome if traveling on a plane.
Cloth Poster
Can be more expensive and may require more lead time, but great for travel!
Spoonflower - Approximately $50+ for 36”x48” or 36”x56”
Poster Nerd - Approximately $110 for 48"x36"
PosterPresentations.com Approximately $115 for 36”x48” or 42”x42”