What is how to shuffle cards?

There are several ways to shuffle cards effectively. Here are a few common methods:

Riffle Shuffle: This is one of the most recognizable and effective shuffling methods. Divide the deck roughly in half. Hold each half with your thumbs along the inside edge and your fingers curled around the outside. Bend the corners of the cards upward, then release them a few at a time, interlacing the two halves. Finally, push the two halves together to complete the shuffle. It is generally accepted that seven riffle shuffles randomize a deck of cards well.
Overhand Shuffle: This is a simpler shuffle. Hold the deck in one hand. With the other hand, take small packets of cards from the top of the deck and move them to the bottom. Repeat this process several times. While easier to perform, it is less effective than a riffle shuffle.
Pile Shuffle: Deal the cards into a number of piles (usually around 5-9) one at a time. Once all the cards are dealt, stack the piles on top of each other. This method is neat, but not very effective at randomization on its own.
Hindu Shuffle (Indian Shuffle): Hold the deck in your non-dominant hand, face down. With your dominant hand, grab a packet of cards from the top and pull it away. Let this packet fall into your dominant hand. Repeat, grabbing packets from the top of the remaining deck and dropping them onto the packets already in your dominant hand.

Important Considerations:

Randomization: The goal of shuffling is to randomize the deck as much as possible. Combining different shuffling methods is often the best way to achieve thorough randomization.
Card Condition: Be gentle to avoid damaging the cards. Avoid bending them excessively.
Table Space: Ensure you have enough space to shuffle comfortably without dropping cards.
Prevention of Stacks/Sequences: Focus on shuffling in a way that separates groups of cards that may have been previously grouped together.