Letters of recommendation are not required for all universities. For example, the UC and CSU systems in California do not require letters of recommendation however, many private schools do. Note that sometimes the universities ask for letters from specific subject teachers. Also, your counselor will most likely need to write a letter. 


For specific information, regarding letters of recommendation, please visit the admissions page for the university (universities) of your interest.  


See the timeline below for an appropriate timeline for asking for letters of recommendation: