Canonical Conundrum Achievement in Halo: The Master Chief Collection

In total, there are 19 Data Pads within the Campaign of Halo: Reach. Specifically, there are two on each main mission of the game and then one more in the "Lone Wolf" mission. Since half of them will only appear when playing on Legendary, it's best to grab them all during any of your Legendary playthroughs.

These collectibles are extremely well-hidden and come in the appearance of a small iPad-like tablet. At times, you will find that some are only obtainable for reaching obscure locations via deep exploration. For an in-depth video guide for all these Data Pads please refer to the video below, courtesy of Halo Completionist.