Growth factor is the factor by which the new size of a C++ STL vector is computed when we need to insert beyond its current capacity. There are containers similar to the STL vector in other languages and it is quite interesting to see what factors were chosen in those implementations.
The last time I looked into this (see this post), VC++ vector had a growth factor of 1.5 and GCC vector had a growth factor of 2.
Java ArrayList seems to have a growth factor of 1.5. See line 240 in ArrayList.java.
Julia also seems to have a growth factor of 1.5.