The text used on a card produces some form of effect. However, this is does not include the Flavor Text, Artist or any copyright and card or set number information.
If the effect requires gameplay actions where they can't all be completed, see "Empty Shot".
Effects written on a card only affect cards that are in the battle zone unless specified on the card itself (such as cards that apply to the deck or mana zone) or only applicable to other game zones (such as discard effects only affecting the hand, or cards that bring others from the Hyperspatial Zone).
Although all effects can stack, some overlap abilities create no difference, such as multiple instances of the same Breaker like a creature having 2x "Double Breaker" abilities.
606.1. An effect is something that happens in the game as a result of using a card or an ability of a card. When a spell, activated ability, or trigger ability resolves, it may create one or more one-shot or continuous effects. Static abilities may create one or more continuous effects. Text itself is never an effect.
606.2. If an effect attempts to do something impossible, it does only as much as possible.
Example: If a player is holding only one card, an effect that reads “Discard two cards” causes them to discard only that card.
606.3. Some continuous effects are replacement effects.