Scoreboard

Francis was an integral member of the Crew's resurgence to the top of MLS since the start of 2014 season. The Costa Rican international was one of the top left backs in MLS in 2014 and 2015, but failed to lockdown the starting left back role in Columbus over the next two seasons. After a year away in Seattle, he looks to regain his starting role in Columbus following an injury to Milton Valenzuela.

ColumbusCrewSC.com: Francis' profile

INTERNATIONAL: Francis has earned six caps with the Costa Rica National Team, most recently starting in a friendly contest against the U.S. Men’s National Team at Avaya Stadium in San Jose, California on February 2 of this year. Notably, Francis was a member of the Costa Rican squad that reached the quarterfinals of the FIFA 2014 World Cup in Brazil.

OUTSIDE MLS: Played for Brujas and Limon in Costa Rica before joining league power Herediano in 2012.

Stats

Player Stats

Game Log

MLS

Career Statistics (Regular Season)

Year	Club	GP	GS	MINS	A	SHTS	SOG	FC	OFF	Y	R
2019	Columbus Crew SC	17	16	1382	0	3	0	23	0	3	0
2018	Seattle Sounders FC	11	5	582	1	1	0	9	0	1	0
2017	Columbus Crew SC	12	10	852	2	8	0	12	1	0	0
2016	Columbus Crew SC	19	13	1233	3	5	1	18	3	2	0
2015	Columbus Crew SC	28	28	2410	7	10	3	30	1	5	0
2014	Columbus Crew	24	24	2111	6	11	3	32	4	5	1
Career Totals	-	111	96	8570	19	38	7	124	9	16	1

Career Statistics (Post Season)

Year	Club	GP	GS	MINS	A	SHTS	FC	OFF	Y
2018	Seattle Sounders FC	1	0	56	0	0	0	2	0
2017	Columbus Crew SC	0	0	0	0	0	0	0	0
2015	Columbus Crew SC	5	5	480	1	4	4	0	0
2014	Columbus Crew	2	2	163	0	1	3	0	1

Regular Season

Date	Match	Result	Appearance	MINS	A	SHTS	SOG	FC	FS	Y	R
10/06/2019	CLB @ TOR	L 0-1	Unused Sub	0	0	0	0	0	0	0	0
9/29/2019	PHI @ CLB	W 0-2	Unused Sub	0	0	0	0	0	0	0	0
9/21/2019	CLB @ VAN	T 1-1	Unused Sub	0	0	0	0	0	0	0	0
9/14/2019	CLB @ ATL	W 3-1	Unused Sub	0	0	0	0	0	0	0	0
8/31/2019	CHI @ CLB	T 1-1	Unused Sub	0	0	0	0	0	0	0	0
8/25/2019	CLB @ CIN	W 3-1	Unused Sub	0	0	0	0	0	0	0	0
8/21/2019	CLB @ NYC	L 0-1	Unused Sub	0	0	0	0	0	0	0	0
8/17/2019	TOR @ CLB	T 2-2	Unused Sub	0	0	0	0	0	0	0	0
8/10/2019	CIN @ CLB	T 2-2	Unused Sub	0	0	0	0	0	0	0	0
8/03/2019	CLB @ SJ	T 1-1	Unused Sub	0	0	0	0	0	0	0	0
7/27/2019	CLB @ RBNY	W 3-2	Unused Sub	0	0	0	0	0	0	0	0
7/20/2019	MTL @ CLB	W 1-2	Started	44	0	0	0	1	0	0	0
7/17/2019	CLB @ CHI	T 2-2	Unused Sub	0	0	0	0	0	0	0	0
7/13/2019	CLB @ ORL	L 0-1	Started	90	0	0	0	1	2	0	0
7/06/2019	SEA @ CLB	L 2-1	Started	90	0	1	0	0	0	0	0
7/03/2019	CLB @ RSL	L 0-1	Subbed on	17	0	0	0	0	0	0	0
6/29/2019	ORL @ CLB	L 2-0	Started	90	0	0	0	0	1	0	0
6/23/2019	SKC @ CLB	L 1-0	Started	61	0	0	0	2	1	0	0
6/01/2019	NYC @ CLB	T 2-2	Unused Sub	0	0	0	0	0	0	0	0
5/25/2019	CLB @ COL	L 2-3	Unused Sub	0	0	0	0	0	0	0	0
5/18/2019	CLB @ MIN	L 0-1	Unused Sub	0	0	0	0	0	0	0	0
5/11/2019	LAFC @ CLB	L 3-0	Unused Sub	0	0	0	0	0	0	0	0
5/08/2019	LA @ CLB	W 1-3	Started	90	0	0	0	1	0	0	0
5/04/2019	CLB @ DC	L 1-3	Started	90	0	0	0	0	1	0	0
4/27/2019	CLB @ HOU	L 0-2	Started	90	0	1	0	5	1	1	0
4/24/2019	DC @ CLB	L 1-0	Started	90	0	0	0	0	1	0	0
4/20/2019	POR @ CLB	L 3-1	Started	90	0	0	0	0	0	0	0
4/13/2019	CLB @ MTL	L 0-1	Started	90	0	0	0	2	0	0	0
4/06/2019	NE @ CLB	W 0-1	Started	90	0	0	0	3	1	0	0
3/30/2019	ATL @ CLB	W 0-2	Started	90	0	0	0	1	1	0	0
3/23/2019	CLB @ PHI	L 0-3	Unused Sub	0	0	0	0	0	0	0	0
3/16/2019	DAL @ CLB	W 0-1	Started	90	0	0	0	3	1	1	0
3/09/2019	CLB @ NE	W 2-0	Started	90	0	0	0	1	0	0	0
3/02/2019	RBNY @ CLB	T 1-1	Started	90	0	1	0	3	0	1	0
10/28/2018	SJ @ SEA	W 1-2	Subbed on	6	0	0	0	0	0	0	0
10/21/2018	SEA @ HOU	W 3-2	Subbed on	8	0	0	0	0	0	0	0
10/17/2018	SEA @ ORL	W 2-1	Subbed on	14	0	0	0	0	0	0	0
10/08/2018	HOU @ SEA	W 1-4	Unused Sub	0	0	0	0	0	0	0	0
9/29/2018	COL @ SEA	W 0-4	Unused Sub	0	0	0	0	0	0	0	0
9/23/2018	SEA @ LA	L 0-3	Unused Sub	0	0	0	0	0	0	0	0
9/19/2018	PHI @ SEA	L 1-0	Unused Sub	0	0	0	0	0	0	0	0
9/15/2018	SEA @ VAN	W 2-1	Unused Sub	0	0	0	0	0	0	0	0
9/01/2018	SKC @ SEA	W 1-3	Unused Sub	0	0	0	0	0	0	0	0
8/26/2018	SEA @ POR	W 1-0	Unused Sub	0	0	0	0	0	0	0	0
8/18/2018	LA @ SEA	W 0-5	Unused Sub	0	0	0	0	0	0	0	0
8/12/2018	DAL @ SEA	W 1-2	Subbed on	17	0	0	0	0	0	0	0
8/04/2018	SEA @ MIN	W 2-1	Subbed on	45	0	0	0	3	0	1	0
7/29/2018	NYC @ SEA	W 1-3	Unused Sub	0	0	0	0	0	0	0	0
7/25/2018	SEA @ SJ	W 1-0	Unused Sub	0	0	0	0	0	0	0	0
7/21/2018	VAN @ SEA	W 0-2	Unused Sub	0	0	0	0	0	0	0	0
7/15/2018	SEA @ ATL	T 1-1	Unused Sub	0	0	0	0	0	0	0	0
7/07/2018	SEA @ NE	T 0-0	Unused Sub	0	0	0	0	0	0	0	0
7/04/2018	SEA @ COL	W 2-1	Started	90	0	0	0	3	1	0	0
6/30/2018	POR @ SEA	L 3-2	Started	81	0	0	0	0	0	0	0
6/23/2018	CHI @ SEA	T 1-1	Unused Sub	0	0	0	0	0	0	0	0
6/13/2018	SEA @ RBNY	L 1-2	Started	90	1	0	0	1	1	0	0
6/09/2018	DC @ SEA	W 1-2	Unused Sub	0	0	0	0	0	0	0	0
6/02/2018	SEA @ RSL	L 0-2	Unused Sub	0	0	0	0	0	0	0	0
5/26/2018	RSL @ SEA	L 1-0	Subbed on	57	0	1	0	0	1	0	0
5/13/2018	SEA @ POR	L 0-1	Unused Sub	0	0	0	0	0	0	0	0
5/09/2018	SEA @ TOR	W 2-1	Started	90	0	0	0	0	0	0	0
5/05/2018	CLB @ SEA	T 0-0	Unused Sub	0	0	0	0	0	0	0	0
4/29/2018	SEA @ LAFC	L 0-1	Unused Sub	0	0	0	0	0	0	0	0
4/22/2018	MIN @ SEA	W 1-3	Unused Sub	0	0	0	0	0	0	0	0
4/15/2018	SEA @ SKC	T 2-2	Unused Sub	0	0	0	0	0	0	0	0
3/31/2018	MTL @ SEA	L 1-0	Started	84	0	0	0	2	1	0	0
3/18/2018	SEA @ DAL	L 0-3	Unused Sub	0	0	0	0	0	0	0	0
3/04/2018	LAFC @ SEA	L 1-0	Unused Sub	0	0	0	0	0	0	0	0
10/22/2017	CLB @ NYC	T 2-2	Unused Sub	0	0	0	0	0	0	0	0
10/15/2017	CLB @ ORL	W 1-0	Unused Sub	0	0	0	0	0	0	0	0
9/30/2017	DC @ CLB	W 0-2	Unused Sub	0	0	0	0	0	0	0	0
9/23/2017	RBNY @ CLB	W 2-3	Unused Sub	0	0	0	0	0	0	0	0
9/16/2017	CLB @ VAN	T 2-2	Unused Sub	0	0	0	0	0	0	0	0
9/10/2017	SKC @ CLB	T 1-1	Unused Sub	0	0	0	0	0	0	0	0
8/26/2017	DAL @ CLB	W 1-2	Unused Sub	0	0	0	0	0	0	0	0
8/23/2017	LA @ CLB	W 0-2	Started	33	0	0	0	1	0	0	0
8/19/2017	CLB @ ORL	T 1-1	Started	90	1	1	0	2	0	0	0
8/12/2017	CHI @ CLB	W 1-3	Started	90	1	0	0	0	0	0	0
8/05/2017	CLB @ SJ	L 1-2	Subbed on	4	0	0	0	0	0	0	0
7/29/2017	CLB @ RSL	T 2-2	Started	78	0	0	0	0	0	0	0
7/26/2017	CLB @ PHI	L 0-3	Unused Sub	0	0	0	0	0	0	0	0
7/22/2017	PHI @ CLB	W 0-1	Unused Sub	0	0	0	0	0	0	0	0
7/04/2017	CLB @ MIN	W 1-0	Unused Sub	0	0	0	0	0	0	0	0
7/01/2017	ATL @ CLB	L 2-0	Unused Sub	0	0	0	0	0	0	0	0
6/24/2017	MTL @ CLB	W 1-4	Unused Sub	0	0	0	0	0	0	0	0
6/17/2017	CLB @ ATL	L 1-3	Unused Sub	0	0	0	0	0	0	0	0
6/03/2017	CLB @ COL	L 1-2	Started	90	0	0	0	1	1	0	0
5/31/2017	SEA @ CLB	W 0-3	Unused Sub	0	0	0	0	0	0	0	0
5/26/2017	CLB @ TOR	L 0-5	Started	90	0	2	0	1	1	0	0
5/21/2017	CLB @ NE	L 1-2	Started	90	0	2	0	3	1	0	0
5/13/2017	CLB @ MTL	W 3-2	Unused Sub	0	0	0	0	0	0	0	0
5/10/2017	TOR @ CLB	L 2-1	Started	90	0	2	0	1	1	0	0
5/06/2017	NE @ CLB	W 0-2	Started	90	0	0	0	2	1	0	0
4/29/2017	NYC @ CLB	L 3-2	Unused Sub	0	0	0	0	0	0	0	0
4/22/2017	CLB @ RBNY	L 0-2	Unused Sub	0	0	0	0	0	0	0	0
4/15/2017	TOR @ CLB	W 1-2	Unused Sub	0	0	0	0	0	0	0	0
4/08/2017	CLB @ CHI	L 0-1	Subbed on	17	0	0	0	1	0	0	0
4/01/2017	ORL @ CLB	W 0-2	Unused Sub	0	0	0	0	0	0	0	0
3/25/2017	POR @ CLB	W 2-3	Started	90	0	1	0	0	1	0	0
3/18/2017	CLB @ DC	W 2-0	Unused Sub	0	0	0	0	0	0	0	0
3/11/2017	CLB @ HOU	L 1-3	Unused Sub	0	0	0	0	0	0	0	0
3/04/2017	CHI @ CLB	T 1-1	Unused Sub	0	0	0	0	0	0	0	0
10/23/2016	CLB @ NYC	L 1-4	Unused Sub	0	0	0	0	0	0	0	0
10/16/2016	CLB @ RBNY	L 2-3	Unused Sub	0	0	0	0	0	0	0	0
10/13/2016	CLB @ CHI	T 2-2	Unused Sub	0	0	0	0	0	0	0	0
10/01/2016	CHI @ CLB	W 0-3	Unused Sub	0	0	0	0	0	0	0	0
9/28/2016	CLB @ DC	L 0-3	Unused Sub	0	0	0	0	0	0	0	0
9/25/2016	NE @ CLB	W 0-2	Unused Sub	0	0	0	0	0	0	0	0
9/17/2016	CLB @ ORL	W 4-1	Unused Sub	0	0	0	0	0	0	0	0
9/10/2016	VAN @ CLB	L 3-1	Subbed on	15	0	0	0	0	0	0	0
9/03/2016	CLB @ LA	L 1-2	Subbed on	25	0	0	0	0	0	0	0
8/27/2016	SJ @ CLB	W 0-2	Unused Sub	0	0	0	0	0	0	0	0
8/24/2016	PHI @ CLB	L 2-1	Unused Sub	0	0	0	0	0	0	0	0
8/20/2016	CLB @ NE	W 2-0	Unused Sub	0	0	0	0	0	0	0	0
8/13/2016	NYC @ CLB	T 3-3	Started	61	1	1	1	0	2	0	0
7/31/2016	CLB @ TOR	L 0-3	Started	90	0	1	0	1	2	0	0
7/23/2016	ORL @ CLB	T 2-2	Unused Sub	0	0	0	0	0	0	0	0
7/16/2016	DC @ CLB	T 1-1	Started	90	0	1	0	3	0	0	0
7/13/2016	TOR @ CLB	T 1-1	Subbed on	1	0	0	0	0	0	0	0
7/09/2016	CLB @ NE	L 1-3	Started	90	0	0	0	1	0	0	0
7/03/2016	CLB @ SKC	L 2-3	Unused Sub	0	0	0	0	0	0	0	0
6/25/2016	RBNY @ CLB	T 1-1	Subbed on	19	1	0	0	1	0	0	0
6/18/2016	MTL @ CLB	T 0-0	Unused Sub	0	0	0	0	0	0	0	0
6/01/2016	CLB @ PHI	L 2-3	Started	90	0	0	0	0	0	0	0
5/28/2016	RSL @ CLB	W 3-4	Subbed on	27	1	0	0	2	1	0	0
5/21/2016	CLB @ TOR	T 0-0	Unused Sub	0	0	0	0	0	0	0	0
5/14/2016	COL @ CLB	T 1-1	Unused Sub	0	0	0	0	0	0	0	0
5/07/2016	MTL @ CLB	T 4-4	Subbed on	21	0	0	0	2	0	1	0
4/30/2016	CLB @ SEA	L 0-1	Started	90	0	1	0	3	0	1	0
4/23/2016	HOU @ CLB	W 0-1	Started	90	0	1	0	2	0	0	0
4/16/2016	NYC @ CLB	W 2-3	Started	90	0	0	0	0	1	0	0
4/09/2016	CLB @ MTL	L 0-2	Started	90	0	0	0	0	1	0	0
4/02/2016	CLB @ DAL	T 1-1	Started	90	0	0	0	1	1	0	0
3/19/2016	CLB @ CHI	T 0-0	Started	90	0	0	0	0	0	0	0
3/12/2016	PHI @ CLB	L 2-1	Started	74	0	0	0	0	0	0	0
3/06/2016	CLB @ POR	L 1-2	Started	90	0	0	0	2	1	0	0
10/25/2015	DC @ CLB	W 0-5	Started	90	1	1	0	0	0	0	0
10/17/2015	CLB @ TOR	W 2-0	Started	90	0	0	0	0	0	0	0
10/03/2015	CLB @ RBNY	L 1-2	Started	90	0	1	1	1	1	0	0
9/26/2015	POR @ CLB	L 2-1	Started	90	0	1	1	2	4	0	0
9/19/2015	CLB @ DC	W 2-1	Unused Sub	0	0	0	0	0	0	0	0
9/12/2015	CLB @ PHI	W 2-1	Started	78	0	0	0	2	0	0	0
9/06/2015	DAL @ CLB	L 3-0	Unused Sub	0	0	0	0	0	0	0	0
8/29/2015	CLB @ NYC	W 2-1	Started	90	0	0	0	0	1	0	0
8/22/2015	SKC @ CLB	W 2-3	Started	90	0	0	0	3	2	0	0
8/19/2015	NYC @ CLB	T 2-2	Started	90	0	1	0	0	1	0	0
8/08/2015	CLB @ COL	W 2-1	Unused Sub	0	0	0	0	0	0	0	0
8/01/2015	CLB @ ORL	L 2-5	Started	90	0	0	0	3	0	1	0
7/25/2015	TOR @ CLB	T 3-3	Started	90	0	0	0	2	0	1	0
7/19/2015	CHI @ CLB	W 1-3	Started	90	1	1	0	6	1	0	0
7/15/2015	CLB @ CHI	W 1-0	Started	90	0	1	0	0	2	0	0
7/11/2015	CLB @ MTL	L 0-3	Started	90	0	0	0	0	0	0	0
7/04/2015	RBNY @ CLB	W 1-2	Started	90	0	1	0	0	1	0	0
6/27/2015	CLB @ RSL	T 2-2	Started	81	0	0	0	1	0	1	0
6/24/2015	NE @ CLB	W 1-2	Started	90	1	0	0	0	1	1	0
6/13/2015	LA @ CLB	T 1-1	Started	90	0	0	0	1	0	0	0
6/06/2015	MTL @ CLB	L 2-1	Started	90	0	1	1	2	1	0	0
6/03/2015	CLB @ PHI	L 0-3	Started	71	0	0	0	0	1	0	0
5/30/2015	CLB @ ORL	T 2-2	Started	90	1	0	0	2	1	1	0
5/22/2015	CHI @ CLB	T 2-2	Started	90	0	0	0	0	0	0	0
5/16/2015	CLB @ SJ	L 0-2	Started	90	0	0	0	3	1	0	0
5/09/2015	SEA @ CLB	W 2-3	Started	90	1	1	0	1	0	0	0
5/02/2015	CLB @ DC	L 0-2	Started	45	0	0	0	0	0	0	0
4/25/2015	PHI @ CLB	W 1-4	Started	90	1	0	0	0	2	0	0
4/18/2015	ORL @ CLB	W 0-3	Started	65	0	1	0	0	3	0	0
4/11/2015	CLB @ NE	T 0-0	Unused Sub	0	0	0	0	0	0	0	0
4/08/2015	CLB @ VAN	T 2-2	Unused Sub	0	0	0	0	0	0	0	0
3/28/2015	RBNY @ CLB	L 2-1	Unused Sub	0	0	0	0	0	0	0	0
3/14/2015	TOR @ CLB	W 0-2	Started	90	1	0	0	0	0	0	0
3/07/2015	CLB @ HOU	L 0-1	Started	90	0	0	0	1	0	0	0
10/26/2014	PHI @ CLB	W 1-2	Started	90	0	1	1	1	1	0	0
10/19/2014	CLB @ RBNY	W 3-1	Unused Sub	0	0	0	0	0	0	0	0
10/11/2014	CLB @ PHI	W 3-2	Unused Sub	0	0	0	0	0	0	0	0
10/04/2014	CLB @ NE	L 1-2	Started	70	0	1	0	2	0	1	1
9/27/2014	MTL @ CLB	W 0-2	Started	90	0	0	0	0	2	0	0
9/20/2014	NE @ CLB	W 0-1	Started	90	0	1	0	1	1	0	0
9/13/2014	CLB @ HOU	T 2-2	Started	90	2	0	0	4	1	1	0
9/07/2014	CHV @ CLB	W 0-3	Started	90	1	1	0	1	0	0	0
8/30/2014	CLB @ MTL	L 0-2	Started	90	0	0	0	3	1	1	0
8/23/2014	HOU @ CLB	W 0-3	Started	90	1	0	0	2	0	0	0
8/16/2014	LA @ CLB	W 1-4	Started	90	0	0	0	2	0	0	0
8/09/2014	TOR @ CLB	L 3-2	Started	90	1	0	0	1	0	0	0
8/02/2014	CLB @ CHI	T 1-1	Started	90	0	1	0	1	1	1	0
7/26/2014	CLB @ NE	W 2-1	Started	90	0	0	0	0	0	0	0
7/19/2014	MTL @ CLB	W 1-2	Started	90	0	1	0	0	1	0	0
7/16/2014	SKC @ CLB	L 2-1	Started	90	0	0	0	2	1	0	0
7/12/2014	CLB @ RBNY	L 1-4	Unused Sub	0	0	0	0	0	0	0	0
7/04/2014	CLB @ COL	T 1-1	Unused Sub	0	0	0	0	0	0	0	0
6/29/2014	DAL @ CLB	T 0-0	Unused Sub	0	0	0	0	0	0	0	0
6/07/2014	CLB @ DC	T 0-0	Unused Sub	0	0	0	0	0	0	0	0
6/04/2014	RSL @ CLB	T 1-1	Unused Sub	0	0	0	0	0	0	0	0
5/31/2014	CLB @ TOR	L 2-3	Unused Sub	0	0	0	0	0	0	0	0
5/24/2014	CHI @ CLB	W 0-2	Unused Sub	0	0	0	0	0	0	0	0
5/17/2014	CLB @ POR	T 3-3	Unused Sub	0	0	0	0	0	0	0	0
5/10/2014	VAN @ CLB	L 1-0	Started	90	0	0	0	1	0	0	0
5/07/2014	CLB @ HOU	L 0-1	Started	90	0	1	1	0	1	0	0
5/04/2014	CLB @ SKC	L 0-2	Started	90	0	0	0	1	1	0	0
4/26/2014	RBNY @ CLB	T 1-1	Started	90	0	1	1	3	1	0	0
4/19/2014	DC @ CLB	T 1-1	Started	62	0	0	0	1	0	0	0
4/13/2014	CLB @ SJ	T 1-1	Started	90	1	1	0	0	0	0	0
4/05/2014	TOR @ CLB	L 2-0	Started	90	0	0	0	0	0	0	0
3/29/2014	CLB @ SEA	W 2-1	Started	90	0	1	0	2	0	0	0
3/22/2014	PHI @ CLB	W 1-2	Started	90	0	0	0	0	0	0	0
3/08/2014	CLB @ DC	W 3-0	Started	89	0	1	0	4	0	1	0

Post Season

Date	Match	Result	Appearance	MINS	A	SHTS	FC	FS	Y
11/08/2018	POR @ SEA	W 2(4)-(2)3	Unused Sub	0	0	0	0	0	0
11/04/2018	SEA @ POR	L 1-2	Subbed on	56	0	0	0	0	0
11/29/2017	CLB @ TOR	L 0-1	Unused Sub	0	0	0	0	0	0
11/21/2017	TOR @ CLB	T 0-0	Unused Sub	0	0	0	0	0	0
11/05/2017	CLB @ NYC	L 0-2	Unused Sub	0	0	0	0	0	0
10/31/2017	NYC @ CLB	W 1-4	Unused Sub	0	0	0	0	0	0
10/26/2017	CLB @ ATL	T 0(3)-(1)0	Unused Sub	0	0	0	0	0	0
12/06/2015	POR @ CLB	L 2-1	Started	90	0	2	1	0	0
11/29/2015	CLB @ RBNY	L 0-1	Started	90	0	1	1	1	0
11/22/2015	RBNY @ CLB	W 0-2	Started	90	0	0	0	1	0
11/08/2015	MTL @ CLB	W 1-3	Started	120	1	0	1	1	0
11/01/2015	CLB @ MTL	L 1-2	Started	90	0	1	1	0	0
11/09/2014	CLB @ NE	L 1-3	Started	90	0	1	1	0	0
11/01/2014	NE @ CLB	L 4-2	Started	73	0	0	2	0	1

Main menu

Scoreboard

Rosters

Waylon Francis

Stats

Waylon Francis Latest News

Waylon Francis Latest Videos