Here is why I ask for PDFs.
When using professional design software, in order to maintain control over images, we “place” or “import’ them into the document. The images are not embedded in the document like word processing software such as Microsoft Word, but they are displayed as an alias in the document. The image is connected into the document by a link to the native image file (.psd, .jpg, .png, etc.) By this method, you keep control over the resolution of the image and can edit it in other programs. If you embed the image, you lose control over it.
Always download images into your project folder. Don’t drag them into your document from the web as most often the images are low res from internet sites unless you are purchasing or downloading from a stock photo website.
Both the fonts and the images you use in your documents must reside on your computer. When transferring files you first need to know:
1) Does the recipient have the software you are working in?
2) Do they have the fonts you are using? and
3) Do they have your images?
If the recipient has the software, but not your fonts or images, when they open up the file they will see each image marked with a red circle with a question mark on it. The software is looking for the links to the images and can’t find them. That is because they are on your computer and haven’t been transferred. This is also why it is important to save your images within your project folders so that they can easily be transported with your file if need be.
If the recipient doesn’t have the fonts you used in your design, they will get an alert upon opening the document that the fonts are missing. If you used a font downloaded from the internet, say from dafont, you will have to send that font to the recipient so they can view your work as you designed it. If the recipient doesn’t have your fonts installed, they won’t show up in the file when opened.
There is a way to “package” your files in InDesign to transfer them if the native files are required. Otherwise, it is better to send a PDF to your client AND to the printer. There are different settings for the quality of the PDF that is being created.
Just as an FYI:
When images are placed into documents, they are simply “alias” images they are not embedded into the file like some other programs. It’s not good to embed images for professional work as you lose control over the quality of them and cannot edit them. Linking images prevents the files from becoming too large to transfer. That is why the industry standard is to make a PDF for the printer. If you proof everything and make sure it is okay before you send to the printer, you are usually okay. But sometimes there are issues with the artwork, at that point you might have to send the “native” files (the InDesign file (.indd), the images and the fonts).
If that is the case, you must PACKAGE the InDesign file. Doing this saves all the images and fonts along with the native InDesign file into a new folder. You usually zip that folder to compress and encode the file to transfer the file through email or upload since there are multiple files to handle. Zipping will also protect the files from getting corrupted. But the issue with this is that the files can become quite large.
So, fortunately technology has helped us with the invention of PDFs (Portable Document Format). When we process our files to be printed, the standard in the industry is to turn our files into PDFs. This embeds the fonts and the images so that you don’t have to be “packaging” files and sending large files to the printer, but keeps your “native” file pure so that if you need to edit anything, you can.
Hope this explanation helps.