Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
List of undefeated boxing world champions
Table title:

Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Boxer </th><th colspan=1 rowspan=1 > Record </th><th colspan=1 rowspan=1 > Weight class </th><th colspan=1 rowspan=1 > Title(s) </th><th colspan=1 rowspan=1 > Championship years </th><th colspan=1 rowspan=1 > Title defenses </th><th colspan=1 rowspan=1 > Notes </th></tr>
<tr> <td colspan=1 rowspan=1 > United States Jimmy Barry </td><td colspan=1 rowspan=1 > 59–0–9 (2) </td><td colspan=1 rowspan=1 > Bantamweight </td><td colspan=1 rowspan=1 > World </td><td colspan=1 rowspan=1 > 1894–1899 </td><td colspan=1 rowspan=1 > 6 (3 draws) </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=5 > United Kingdom Joe Calzaghe </td><td colspan=1 rowspan=5 > 46–0–0 (0) </td><td colspan=1 rowspan=4 > Super middleweight </td><td colspan=1 rowspan=1 > WBO </td><td colspan=1 rowspan=1 > 1997–2008 </td><td colspan=1 rowspan=1 > 21 </td><td colspan=1 rowspan=1 > Vacated title to move up to light heavyweight. </td></tr>
<tr> <td colspan=1 rowspan=1 > IBF </td><td colspan=1 rowspan=1 > 2006 </td><td colspan=1 rowspan=1 > 1 </td><td colspan=1 rowspan=1 > Vacated title to fight Peter Manfredo Jr. instead of #1 contender Robert Stieglitz. </td></tr>
<tr> <td colspan=1 rowspan=1 > The Ring, lineal </td><td colspan=1 rowspan=1 > 2006–2008 </td><td colspan=1 rowspan=1 > 3 </td><td colspan=1 rowspan=2 > Vacated titles to move up to light heavyweight. </td></tr>
<tr> <td colspan=1 rowspan=1 > WBA, WBC </td><td colspan=1 rowspan=1 > 2007–2008 </td><td colspan=1 rowspan=1 > 0 </td></tr>
<tr> <td colspan=1 rowspan=1 > Light heavyweight </td><td colspan=1 rowspan=1 > The Ring </td><td colspan=1 rowspan=1 > 2008 </td><td colspan=1 rowspan=1 > 1 </td><td colspan=1 rowspan=1 > Retired and vacated title. </td></tr>
<tr> <td colspan=1 rowspan=1 > South Korea Kim Ji-won </td><td colspan=1 rowspan=1 > 16–0–2 (0) </td><td colspan=1 rowspan=1 > Super bantamweight </td><td colspan=1 rowspan=1 > IBF </td><td colspan=1 rowspan=1 > 1985–1986 </td><td colspan=1 rowspan=1 > 4 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Romania Mihai Leu </td><td colspan=1 rowspan=1 > 28–0–0 (0) </td><td colspan=1 rowspan=1 > Welterweight </td><td colspan=1 rowspan=1 > WBO </td><td colspan=1 rowspan=1 > 1997 </td><td colspan=1 rowspan=1 > 1 </td><td colspan=1 rowspan=1 > Retired from boxing due to an injury. </td></tr>
<tr> <td colspan=1 rowspan=4 > Mexico Ricardo López </td><td colspan=1 rowspan=4 > 51–0–1 (0) </td><td colspan=1 rowspan=3 > Minimumweight </td><td colspan=1 rowspan=1 > WBC </td><td colspan=1 rowspan=1 > 1990–1998 </td><td colspan=1 rowspan=1 > 22 </td><td colspan=1 rowspan=1 > Vacated title to move up to light flyweight. </td></tr>
<tr> <td colspan=1 rowspan=1 > WBO </td><td colspan=1 rowspan=1 > 1997–1998 </td><td colspan=1 rowspan=1 > 0 </td><td colspan=1 rowspan=1 > Unified WBC and WBO titles. Stripped of WBO title for saying he wanted to give the belt to his father. </td></tr>
<tr> <td colspan=1 rowspan=1 > WBA </td><td colspan=1 rowspan=1 > 1998 </td><td colspan=1 rowspan=1 > 0 </td><td colspan=1 rowspan=1 > Vacated title to move up to junior flyweight. </td></tr>
<tr> <td colspan=1 rowspan=1 > Light flyweight </td><td colspan=1 rowspan=1 > IBF </td><td colspan=1 rowspan=1 > 1999–2002 </td><td colspan=1 rowspan=1 > 2 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > United States Rocky Marciano </td><td colspan=1 rowspan=1 > 49–0–0 (0) </td><td colspan=1 rowspan=1 > Heavyweight </td><td colspan=1 rowspan=1 > World </td><td colspan=1 rowspan=1 > 1952–1956 </td><td colspan=1 rowspan=1 > 6 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > United Kingdom Terry Marsh </td><td colspan=1 rowspan=1 > 26–0–1 (0) </td><td colspan=1 rowspan=1 > Light welterweight </td><td colspan=1 rowspan=1 > IBF </td><td colspan=1 rowspan=1 > 1987 </td><td colspan=1 rowspan=1 > 1 </td><td colspan=1 rowspan=1 > Retired from boxing due to epilepsy. </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=5 > United States Floyd Mayweather Jr. </td><td colspan=1 rowspan=5 > 50–0–0 (0) </td><td class="highlighted"  colspan=1 rowspan=1 > Super featherweight </td><td colspan=1 rowspan=1 > WBC </td><td colspan=1 rowspan=1 > 1998–2002 </td><td colspan=1 rowspan=1 > 8 </td><td colspan=1 rowspan=1 > Vacated title to move up to lightweight. </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Lightweight </td><td colspan=1 rowspan=1 > WBC </td><td colspan=1 rowspan=1 > 2002–2004 </td><td colspan=1 rowspan=1 > 3 </td><td colspan=1 rowspan=1 > Vacated title to move up to light welterweight. </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Light welterweight </td><td colspan=1 rowspan=1 > WBC </td><td colspan=1 rowspan=1 > 2005–2006 </td><td colspan=1 rowspan=1 > 0 </td><td colspan=1 rowspan=1 > Vacated title to move up to welterweight. </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Welterweight </td><td colspan=1 rowspan=1 > WBA, WBC </td><td colspan=1 rowspan=1 > 2006–2008, 2011–2015 </td><td colspan=1 rowspan=1 > 8 </td><td class="highlighted"  colspan=1 rowspan=2 > Retired at 49–0 in 2015; returned in 2017 for non-title McGregor fight and then retired again. </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Light middleweight </td><td colspan=1 rowspan=1 > WBA, WBC </td><td colspan=1 rowspan=1 > 2007, 2012–2015, 2017 </td><td colspan=1 rowspan=1 > 2 </td></tr>
<tr> <td colspan=1 rowspan=1 > Republic of Ireland Jack McAuliffe </td><td colspan=1 rowspan=1 > 30–0–5 (1) </td><td colspan=1 rowspan=1 > Lightweight </td><td colspan=1 rowspan=1 > World </td><td colspan=1 rowspan=1 > 1886–1893 </td><td colspan=1 rowspan=1 > 7–0–2 (0) </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=2 > Germany Sven Ottke </td><td colspan=1 rowspan=2 > 34–0–0 (0) </td><td colspan=1 rowspan=2 > Super middleweight </td><td colspan=1 rowspan=1 > IBF </td><td colspan=1 rowspan=1 > 1998–2004 </td><td colspan=1 rowspan=1 > 21 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > WBA </td><td colspan=1 rowspan=1 > 2003–2004 </td><td colspan=1 rowspan=1 > 4 </td><td colspan=1 rowspan=1 > Defended IBF title and defeated WBA champion to become WBA Super champion. </td></tr>
<tr> <td colspan=1 rowspan=1 > Russia Dmitry Pirog </td><td colspan=1 rowspan=1 > 20–0–0 (0) </td><td colspan=1 rowspan=1 > Middleweight </td><td colspan=1 rowspan=1 > WBO </td><td colspan=1 rowspan=1 > 2010–2012 </td><td colspan=1 rowspan=1 > 3 </td><td colspan=1 rowspan=1 > Retired from boxing due to chronic back injuries. </td></tr>
<tr> <td colspan=1 rowspan=2 > Namibia Harry Simon </td><td colspan=1 rowspan=2 > 31–0–0 (0) </td><td colspan=1 rowspan=1 > Light middleweight </td><td colspan=1 rowspan=1 > WBO </td><td colspan=1 rowspan=1 > 1998–2001 </td><td colspan=1 rowspan=1 > 4 </td><td colspan=1 rowspan=1 > Vacated title to move up to middleweight. </td></tr>
<tr> <td colspan=1 rowspan=1 > Middleweight </td><td colspan=1 rowspan=1 > WBO </td><td colspan=1 rowspan=1 > 2002 </td><td colspan=1 rowspan=1 > 0 </td><td colspan=1 rowspan=1 > Won WBO interim middleweight title in 2001 and the outright title in 2002. Stripped of title at 22–0 when he was unable to defend it due to injuries suffered in a car crash. </td></tr>
<tr> <td colspan=1 rowspan=1 > Thailand Pichit Sitbangprachan </td><td colspan=1 rowspan=1 > 24–0–0 (0) </td><td colspan=1 rowspan=1 > Flyweight </td><td colspan=1 rowspan=1 > IBF </td><td colspan=1 rowspan=1 > 1992–1994 </td><td colspan=1 rowspan=1 > 5 </td><td colspan=1 rowspan=1 > Retired at 21–0 and then made a comeback. </td></tr>
<tr> <td colspan=1 rowspan=2 > Venezuela Edwin Valero </td><td colspan=1 rowspan=2 > 27–0–0 (0) </td><td colspan=1 rowspan=1 > Super featherweight </td><td colspan=1 rowspan=1 > WBA </td><td colspan=1 rowspan=1 > 2006–2008 </td><td colspan=1 rowspan=1 > 4 </td><td colspan=1 rowspan=1 > Vacated title to move up to lightweight. </td></tr>
<tr> <td colspan=1 rowspan=1 > Lightweight </td><td colspan=1 rowspan=1 > WBC </td><td colspan=1 rowspan=1 > 2009–2010 </td><td colspan=1 rowspan=1 > 2 </td><td colspan=1 rowspan=1 > Vacated title to move up to light welterweight. Committed suicide after allegedly killing his wife in 2010. </td></tr>
<tr> <td colspan=1 rowspan=3 > United States Andre Ward </td><td colspan=1 rowspan=3 > 32–0–0 (0) </td><td colspan=1 rowspan=2 > Super middleweight </td><td colspan=1 rowspan=1 > WBA </td><td colspan=1 rowspan=1 > 2009–2015 </td><td colspan=1 rowspan=1 > 6 </td><td colspan=1 rowspan=2 > Vacated titles in 2015 to move up to light heavyweight. </td></tr>
<tr> <td colspan=1 rowspan=1 > WBC, The Ring, lineal </td><td colspan=1 rowspan=1 > 2011–2015 </td><td colspan=1 rowspan=1 > 1 (WBC), 2 (The Ring, lineal) </td></tr>
<tr> <td colspan=1 rowspan=1 > Light heavyweight </td><td colspan=1 rowspan=1 > WBA, WBO, The Ring, lineal </td><td colspan=1 rowspan=1 > 2016–2017 </td><td colspan=1 rowspan=1 > 1 (WBA, IBF, WBO), 0 (The Ring, lineal) </td><td colspan=1 rowspan=1 >  </td></tr>
</table>
Question:
What is Floyd Mayweather's Jr.'s overall career record, and in how many weight classes did he earn world titles?
Answer:
In Floyd Mayweather Jr.'s career, he held multiple world titles in five weight classes (twice at welterweight) and retired with an undefeated record.