Small-outline transistor
A small outline transistor (SOT) is a family of small footprint, discrete surface mount transistor commonly used in consumer electronics.  The most common SOT are SOT23 variations,. SOT23-5 differs from SOT23 in a wider body of  instead of . Also, manufacturers offer the nearly identical thin small outline transistor (TSOT/TSOP) package, where lower height is important.

SOT23, SOT323, SOT416
The SOT23 package is very popular and a common package for transistors, as well as diodes and voltage regulators.

SOT23-5, SOT353, SOT553

SOT23-6, SOT363, SOT563

SOT23-8

SOT54
SOT54 is an alternate designation for the JEDEC TO-92 package.

SOT23-4, SOT143, SOT343

SOT490

SOT89-3
The SOT89-3 electrically only has three leads (contact/pin). The wide lead (tab) is physically part of the middle lead on the other side of the package. Some call this package a SOT89-4, since it visually appears to have four leads when looking down at the part.

SOT89-5
The SOT89-5 electrically only has five leads (contact/pin). The middle lead is physically part of the middle lead on the other side of the package. Some call this package a SOT89-6, since it visually appears to have six leads when looking down at the part.

SOT223 (SOT223-4)
The SOT223-4 package is a popular package for voltage regulators. It was introduced by Philips.

SOT223-5
The SOT223-5 package is a popular package for voltage regulators.

SOT223-8
The SOT223-8 package is a popular package for bridged quad transistors.

See also
 List of electronics package dimensions

References

Semiconductor packages