Almost all universities in US have tri-semester system named as Spring, Summer and Fall.
The Fall semester (Starts in August / September )
The Fall semester is the first semester of US academic year and its start in the month of August. This is often called as autumn semester. The Fall semester last long for 13 weeks till the end of December or mid of January. Normally students start their application process even a year before to secure their education in the Fall semester. Some of the universities accept application only for Fall semester.
The Spring semester (Starts in January)
The spring semester classes would start in the first or second week of January in most of the colleges and universities. Majority of universities process admission for new students during spring semester, but the student intake would be minimal compared to fall semester. The Spring semester durations would be of 16 to 18 weeks. You must plan to apply for the spring semester in the month of July of the year before. Some of the universities have spring semester application deadlines as September or October. During the spring semester, students can do their part time jobs to cover their expenses of living, accommodation and other expenses. Some of the universities call the spring semester as winter semester, so do not confuse between two semesters.
The Summer semester (Starts in June)
Summer semester is the shortest of the three semesters and with duration of two months and typically begins in the month of June. Some of the universities has restriction for summer intake. Even though the university as the whole may have summer intake, but some of the department may not accept new students. The Summer semester usually consists of 10 to 12 weeks. Normally, Summer semester is divided into several sessions, such as Summer session I, Summer session II, etc.
Title: What is Spring, Summer and Fall semesters in US Admission cycle?