Instead of giving checkmate, I gave stalemate. Why?

Question

I am a beginner, and I have just discovered this annoying stalemate. I got the definition but while playing, I ended up with a stalemate and I don't know why, could you help me and explain it to me?

2 possibilities: 1- You can find attached the link to board's screenshot with the pieces positions:

2- Or the following explanation: I had 4 rooks that were supposed to block the king so he could not move anymore (and thus I was expecting a checkmate): Positions: - The king: c3 - The 4 rooks: b1, d1 (so the king couldn't move horizontally), and h2, h4 (so the king couldn't move vertically).

Isn't this supposed to be checkmate?

Answer 1

No; for checkmate, the king must be in check, i.e. attacked by one of your pieces. This isn't the case in the position you posted, but if you were to move, you'd be able to force mate in two:

[FEN "8/8/4K3/8/6R1/2k5/7R/1R1R4 w - - 0 1"]

1. Rh3+ Kc2 2. Rg2#

Actually, you don't need that many rooks to checkmate. A lone king and rook will be enough; the procedure is explained in this Wikipedia article.

Answer 2

For checkmate you need to be able to capture the enemy king in the next move and your opponent must not have any way to prevent this.

Alternatively this can be defined by two rules that have to be satisfied simultaneously:

1. all escape squares of the king are taken; either blocked by pieces of the king's color or (as in your case) covered by the checkmating side
2. the king is in check (i.e. attacked) and cannot (a) capture the piece which gives check; nor (b) put a piece between the piece which gives check and the king so that the check is interrupted (this would only work for bishop, rook and queen checks)

In your case only "1" is satisfied, so it is not checkmate.