Ian Williams isn't new to the San Francisco 49ers, but the defensive lineman now knows he'll remain in the Bay Area for at least another season. The team announced a one-year contract with its starting nose tackle on Wednesday to take him off of the free-agent market.

Williams started all 16 games in 2015 and recorded a career high 65 tackles.

For those who need a refresher, here are five things to know about No. 93.

1. He was an undrafted free agent in 2011

The Notre Dame alum went under the radar on his path to the NFL. San Francisco scooped Williams up after he went undrafted and made the defensive lineman earn his keep. Williams did just that.

He made the 53-man roster out of training camp in 2011 and appeared in one game as a rookie. Williams' first start came in 2013, but an injury ended his season prematurely. Despite the missed time, San Francisco had still seen enough to extend Williams for two years through 2015. Williams rewarded the 49ers with a clean bill of health last season as he anchored the team's defensive line.

2. He's a beast against the run

According to Pro Football Focus, Williams' 37 run stops last season were tied for third in the NFL along with St. Louis Rams defensive lineman Aaron Donald.

PFF graded Williams positively in most games in 2015, but his most notable mark came in Week 16 against the Detroit Lions. San Francisco's nose tackle earned a grade of +5.0 that day thanks to a game-high five run stops.

"It's time to start viewing Ian Williams as one of the best run-plugging nose tackles in the league," wrote PFF in its game recap.

Additionally, the website called Williams "one of the best players that nobody talks about."

3. He's really entertaining when he's mic'd up

49ers Studios had a mic on Williams during a home preseason contest last year against the Dallas Cowboys. Among the events of that game was NaVorro Bowman's return to the field. The highlight of the micing, however, was Williams' reaction to Mike Purcell's pick-six.

We suggest you watch the entire piece, but jump to the 2:06 mark if you just want to see the Purcell interception.

4. He's a staple at 49ers community events

Williams is in attendance at just about all of the 49ers community events. The lineman's inclination to give back earned him the organization's Perry/Yonamine Unity Award this past year, given to the 49ers player who exhibits an exceptional commitment to promoting unity within the team and the community.

"It means a lot to be the recipient of the Perry/Yonamine Unity Award," said Williams. "Knowing what your teammates think of you, not even telling you to your face but just knowing what they think of you in their heads, how respected you are in the locker room, that means a lot to me."

In addition, Williams is a prominent member of his community back in his hometown of Orlando, Fla.

5. You can follow him on social media

Williams is on Twitter (@IWilliams95) and Instagram (@iwilliams93). Here is a taste of what you get once you follow those accounts.