When converting raw image to tif?

It saves 100% of the quality

Jpeg at lowest compression has also good quality, but you can't use them if you want to edit/adjust colors in photoshop

You have to convert your RAW to some other format in in order to print, share, post or do anything else with it. TIF is a lossless format and will not degrade the image. TIF's are a much larger file and are very difficult to post and share online. JPEG compresses the image and the image will degrade slightly every time you save or move the file. 1st generation JPEG (1st save) are still very high quality and I use them all the time for printing, even up to poster size.

Don't ever get rid of the RAW file. If you ever want to modify the photo, you will want to go back to the RAW. Do not modify JPEG's, or TIF's, you will not get as good as quality.

As far as what you see on the screen (or on paper, if you print it), no, nothing is lost.

What is lost is a whole lot of exposure information your computer can use when you edit. So TIF is a good form to convert to from RAW if you're printing, or if you plan on moving/saving the file around a lot.

For web uses though, JPG is the undisputed king.

Not much is lost in converting to tif, but a substantial amount is lost going to jpg.

once you convert FROM RAW you always lose something...