I am trying to display a Powerpoint slide deck on an android tablet, but the slides contain fonts that don't exist in android.
Is there a way to install custom fonts on the tablet? If so, how?
In general, no. Some apps will let you add extra fonts to your SD card and search for then there, but that's app-specific.
If your device is rooted, you could replace the built in fonts with those of your choosing, but that's a system-wide change.
Yes, you can install new fonts, but it requires root on most devices.
To install a font, you just simply need to copy the font file (.ttf format only) into /system/fonts. There are also numerous apps available on the Play store to do this automatically for you. Some apps also include functionality to find new fonts.
With an app such as iFont, it is also possible to install fonts without root on the Samsung Galaxy S3, S4, Note, and Note 2.