Pauper Commander, also known as PDH (Pauper EDH), is a variant of Commander (EDH) that combines the rules of the Commander format with the card pool restrictions of Pauper. In Pauper, only cards that have been printed at the common rarity in any Magic: The Gathering set are allowed. This means that in Pauper Commander, your deck can only contain cards that are commons, and your Commander must also be an uncommon creature. 

Pauper Commander decks are 100 cards, with 1 Commander and 99 other cards. If you are choosing a background or partner creature, the deck consists of 98 cards. The rest of the rules follow the traditional Commander rules, such as the singleton rule (only one copy of any card, except basic lands), the starting life total of 30, and the Commander damage rule (where a player loses if they are dealt 16 or more combat damage by a single Commander throughout the game).

The format can be quite budget-friendly compared to regular Commander, as many of the cards are inexpensive due to their common rarity. This makes Pauper Commander a popular choice for players looking for a more casual, budget-friendly Commander experience.