Soong-type androids are the line of synthetic beings created by Dr. Noonien Soong and his successors, including Data, Lore and B-4.
Noonien Soong spent his life trying to create a truly sentient android. B-4 was an early, limited prototype, while Lore was a more complex but unstable model. Data, made afterwards, became the first android to serve in Starfleet.
The line was extended in later years. Data built Lal using his own design, and Soong created an android version of his wife, Juliana. After Data's death, research based on his neural patterns led Bruce Maddox and Altan Inigo Soong to create synthetic twins, Dahj and Soji, and a community of synths on Coppelius.
These androids raised enduring questions about rights and personhood that Starfleet and the Federation struggled to answer, from Data's hearing in 2365 to the synth ban that followed the attack on Mars in 2385.