"TE" is derived from its components: Tris, a common pH buffer, and EDTA, a molecule that chelates cations like Mg2+.
The purpose of TE buffer is to solubilize DNA or RNA, while protecting it from degradation.
[1] Genomic and plasmid DNA can be stored in TE Buffer at 4 °C (39.2 °F) for short-term use, or -20 °C (-4 °F) to -80 °C (-112 °F) for long-term storage.
There is a version of TE buffer with 10 times less amount of EDTA that is very frequently used for the forensic STR kits.
Due to the use of kits with multiplex amplification, it is necessary to have a lower amount of EDTA in the sample so as not to interfere with the Mg2+ present in the reaction.