Robinson

Robinson used to after opening 1nt opponent, you must have at least 10 points and 8 high-card points.
2C shows 2 majors,

2D shows a single-suited major,

2H shows hearts + minor,

2S shows spades + minor,

Double shows a 5+ card minor and a 4-card major.

If partner bid 2C, You will choose his best major.

If partner bid 2D, You will bid 2H asking you to pass or correct.

If partner double, You will bid 2C, partner pass if clubs or correct to 2D if diamonds,

You will bid 2D if he wants to play in a major.

You will bid 2H a natural 5+ card suit

You will bid 2S a natural 5+ card suit

If partner bid 2H, You will pass or 2 NT asking partner for his/her minor suit

If partner bid 2S, You will pass or 2 NT asking partner for his/her minor suit