A palindromic sequence is a DNA or RNA sequence that reads the same on the complementary strand. It is not a sequence that reads the same forwards and backwards.

Thus:

• AATCGCGATT is a palindromic sequence,
• AATCGGCTAA is not

Palindromic sequences are interesting because they are hotspots for mutation. Palindromic DNA sequences in Bacteria appear to be more prone to mutation than non-palindromic sequences.