按钮位75bb防守（BTN 75bb Defense）

## Overview
BTN 75bb Defense refers to the defensive actions taken by a player on the button (BTN) when facing a raise (typically from the blinds or an earlier position) with an effective stack depth of approximately 75 big blinds (bb). This term is commonly used in discussions about range construction and strategic adjustments at medium stack depths (typically 50-100bb).

## Key Strategic Points
- **Frequency and Range**: The [button](/term/button) has the strongest positional advantage, so its defense range is usually wider. At 75bb depth, the player will call or [3-bet](/term/3bet) a portion of hands to balance value and bluffs. A typical defense range includes: calling (flat [call](/term/call)) around 15%-25% of starting hands, and [3-betting](/term/3bet) around 6%-10%. The exact range depends on the opponent's raise size, style, and subsequent actions.
- **Positional Advantage**: The [button](/term/button) always has position post-flop, so it can defend with more speculative hands (e.g., small pairs, [suited connectors](/term/suited-connectors)), hoping to use position to make better decisions after the flop.
- **Stack Depth Considerations**: 75bb is a medium depth, allowing effective all-in threats after a 3-[bet](/term/bet) while retaining enough remaining chips for multi-street play post-flop. Compared to shallow stacks (e.g., 20bb), the defense range is wider and emphasizes post-flop skill.
- **Against Different Opponents**: Against tight players, the defense range can be tightened; against loose raisers, increase calling and use 3-[bets](/term/bet) to punish.

## Example (Typical Scenario)
Assume the opponent opens from the [CO position to 2.5bb](/term/co-open-raise) with an effective stack of 75bb. The button can defend with the following hand types:
- Call: [Suited connectors](/term/suited-connectors) (e.g., [65s](/term/65s)), small pairs ([22](/term/22)-[77](/term/77)), some Ace-high hands (e.g., [A9s](/term/a9s)-[A2s](/term/a2s))
- 3-bet to 8-10bb: Value hands (e.g., [TT](/term/tt)+, AJ+, KQ) and bluff hands (e.g., [A5s](/term/a5s), [K9s](/term/k9s))
The actual range should be adjusted based on the opponent.

## Notes
- Avoid over-defending: Against larger raises (e.g., 4bb+) or from tight opponents, tighten the range to prevent exploitation.
- Post-flop plan: After calling, consider how the flop fits your range. For example, small pairs should often fold when they miss the flop.
- Balanced strategy: The [3-bet range](/term/3-bet-range) must include enough bluffs to prevent frequent [4-bet](/term/4-bet) retaliation from opponents.